diff --git a/intelligence_finance_v1/client.go b/intelligence_finance_v1/client.go
new file mode 100644
index 0000000..a889c00
--- /dev/null
+++ b/intelligence_finance_v1/client.go
@@ -0,0 +1,345 @@
+package intelligence_finance_v1
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+)
+
+const (
+	// DefaultTimeout 默认请求超时时间
+	DefaultTimeout = 30 * time.Second
+	// DefaultNonceLength 默认随机数长度
+	DefaultNonceLength = 16
+	// HeaderTenantID 租户ID请求头
+	HeaderTenantID = "tenant-id"
+	// HeaderClientID 应用标识请求头
+	HeaderClientID = "client-id"
+	// HeaderSignatureTimestamp 签名时间戳请求头
+	HeaderSignatureTimestamp = "x-bfl-signature-timestamp"
+	// HeaderSignatureNonce 签名随机数请求头
+	HeaderSignatureNonce = "x-bfl-signature-nonce"
+	// HeaderSignature 签名信息请求头
+	HeaderSignature = "x-bfl-signature"
+	// ClientIDDingTalk 钉钉AI表格的固定 client-id
+	ClientIDDingTalk = "dd-ai-table"
+)
+
+// Client 业财连接 SDK 客户端
+// 用于调用平台提供的接口（订单开票、开票状态查询、创建付款单据、支付状态查询）
+// 以及处理平台回调通知
+type Client struct {
+	// BaseURL 平台接口基础地址
+	BaseURL string
+	// TenantID 平台分配的租户唯一标识
+	TenantID string
+	// ClientID 平台分配的应用标识
+	ClientID string
+	// ClientSecret 平台分配的密钥，用于签名
+	ClientSecret string
+	// HTTPClient HTTP 客户端
+	HTTPClient *http.Client
+	// NonceLength 随机数长度
+	NonceLength int
+}
+
+// ClientOption 客户端配置选项
+type ClientOption func(*Client)
+
+// WithHTTPClient 设置自定义 HTTP 客户端
+func WithHTTPClient(httpClient *http.Client) ClientOption {
+	return func(c *Client) {
+		c.HTTPClient = httpClient
+	}
+}
+
+// WithNonceLength 设置随机数长度
+func WithNonceLength(length int) ClientOption {
+	return func(c *Client) {
+		c.NonceLength = length
+	}
+}
+
+// NewClient 创建一个新的业财连接客户端
+// baseURL: 平台接口基础地址（如 "https://api.example.com"）
+// tenantID: 平台分配的租户唯一标识
+// clientID: 平台分配的应用标识（钉钉AI表格固定为 "dd-ai-table"）
+// clientSecret: 平台分配的密钥
+func NewClient(baseURL, tenantID, clientID, clientSecret string, opts ...ClientOption) *Client {
+	c := &Client{
+		BaseURL:      baseURL,
+		TenantID:     tenantID,
+		ClientID:     clientID,
+		ClientSecret: clientSecret,
+		HTTPClient: &http.Client{
+			Timeout: DefaultTimeout,
+		},
+		NonceLength: DefaultNonceLength,
+	}
+	for _, opt := range opts {
+		opt(c)
+	}
+	return c
+}
+
+// NewDingTalkClient 创建一个钉钉AI表格专用的客户端
+// baseURL: 平台接口基础地址
+// tenantID: 平台分配的租户唯一标识
+// clientSecret: 平台分配的密钥（在钉钉AI表格中配置为 APPSecret）
+// 注意：钉钉AI表格的 client-id 固定为 "dd-ai-table"，签名由AI表格自动完成
+func NewDingTalkClient(baseURL, tenantID, clientSecret string, opts ...ClientOption) *Client {
+	return NewClient(baseURL, tenantID, ClientIDDingTalk, clientSecret, opts...)
+}
+
+// ============================================================================
+// 签名相关方法
+// ============================================================================
+
+// buildSignature 构建请求签名
+// 签名算法：HmacSHA256(client-secret, timestamp + nonce)，结果 Base64 编码
+func (c *Client) buildSignature(timestamp, nonce string) string {
+	data := timestamp + nonce
+	return HmacSHA256Sign(c.ClientSecret, data)
+}
+
+// setAuthHeaders 设置认证请求头
+func (c *Client) setAuthHeaders(req *http.Request, timestamp, nonce string) {
+	req.Header.Set(HeaderTenantID, c.TenantID)
+	req.Header.Set(HeaderClientID, c.ClientID)
+	req.Header.Set(HeaderSignatureTimestamp, timestamp)
+	req.Header.Set(HeaderSignatureNonce, nonce)
+	req.Header.Set(HeaderSignature, c.buildSignature(timestamp, nonce))
+	req.Header.Set("Content-Type", "application/json")
+}
+
+// ============================================================================
+// 内部 HTTP 请求方法
+// ============================================================================
+
+// doRequest 执行带签名的 POST 请求
+func (c *Client) doRequest(ctx context.Context, path string, requestBody interface{}) (*commonResponse, error) {
+	bodyBytes, err := json.Marshal(requestBody)
+	if err != nil {
+		return nil, fmt.Errorf("marshal request body: %w", err)
+	}
+
+	url := c.BaseURL + path
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(bodyBytes))
+	if err != nil {
+		return nil, fmt.Errorf("create request: %w", err)
+	}
+
+	timestamp := GenerateTimestamp()
+	nonce, err := GenerateNonce(c.NonceLength)
+	if err != nil {
+		return nil, fmt.Errorf("generate nonce: %w", err)
+	}
+
+	c.setAuthHeaders(req, timestamp, nonce)
+
+	resp, err := c.HTTPClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("execute request: %w", err)
+	}
+	defer resp.Body.Close()
+
+	respBody, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("read response body: %w", err)
+	}
+
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		return nil, fmt.Errorf("unexpected HTTP status: %d, body: %s", resp.StatusCode, string(respBody))
+	}
+
+	var commonResp commonResponse
+	if err := json.Unmarshal(respBody, &commonResp); err != nil {
+		return nil, fmt.Errorf("unmarshal response: %w", err)
+	}
+
+	if commonResp.Code != 0 {
+		return nil, NewAPIError(commonResp.Code, commonResp.Msg)
+	}
+
+	return &commonResp, nil
+}
+
+// ============================================================================
+// 接口 1：订单开票
+// ============================================================================
+
+// CreateInvoice 提交订单开票请求
+// path: 接口路径（接口短码，由平台对接时分配）
+// req: 开票请求参数
+// 返回开票响应，包含开票状态和发票数据列表
+func (c *Client) CreateInvoice(ctx context.Context, path string, req *InvoiceRequest) (*InvoiceResponse, error) {
+	commonResp, err := c.doRequest(ctx, path, req)
+	if err != nil {
+		return nil, err
+	}
+
+	// 将 data 字段重新序列化后反序列化为 InvoiceResponse
+	dataBytes, err := json.Marshal(commonResp.Data)
+	if err != nil {
+		return nil, fmt.Errorf("marshal response data: %w", err)
+	}
+
+	var invoiceResp InvoiceResponse
+	if err := json.Unmarshal(dataBytes, &invoiceResp); err != nil {
+		return nil, fmt.Errorf("unmarshal invoice response: %w", err)
+	}
+
+	return &invoiceResp, nil
+}
+
+// ============================================================================
+// 接口 2：开票状态查询
+// ============================================================================
+
+// QueryInvoiceStatus 查询订单开票状态
+// path: 接口路径（接口短码，由平台对接时分配）
+// req: 查询请求参数
+// 返回开票状态查询响应
+func (c *Client) QueryInvoiceStatus(ctx context.Context, path string, req *InvoiceStatusQueryRequest) (*InvoiceStatusQueryResponse, error) {
+	commonResp, err := c.doRequest(ctx, path, req)
+	if err != nil {
+		return nil, err
+	}
+
+	dataBytes, err := json.Marshal(commonResp.Data)
+	if err != nil {
+		return nil, fmt.Errorf("marshal response data: %w", err)
+	}
+
+	var statusResp InvoiceStatusQueryResponse
+	if err := json.Unmarshal(dataBytes, &statusResp); err != nil {
+		return nil, fmt.Errorf("unmarshal invoice status response: %w", err)
+	}
+
+	return &statusResp, nil
+}
+
+// ============================================================================
+// 接口 3：创建付款单据
+// ============================================================================
+
+// CreatePaymentDocument 创建付款单据
+// path: 接口路径（接口短码，由平台对接时分配）
+// req: 付款单据请求参数
+// 返回创建结果，包含单据唯一标识
+func (c *Client) CreatePaymentDocument(ctx context.Context, path string, req *PaymentDocumentRequest) (*PaymentDocumentResponse, error) {
+	commonResp, err := c.doRequest(ctx, path, req)
+	if err != nil {
+		return nil, err
+	}
+
+	dataBytes, err := json.Marshal(commonResp.Data)
+	if err != nil {
+		return nil, fmt.Errorf("marshal response data: %w", err)
+	}
+
+	var paymentResp PaymentDocumentResponse
+	if err := json.Unmarshal(dataBytes, &paymentResp); err != nil {
+		return nil, fmt.Errorf("unmarshal payment document response: %w", err)
+	}
+
+	return &paymentResp, nil
+}
+
+// ============================================================================
+// 接口 5：支付状态查询
+// ============================================================================
+
+// QueryPaymentStatus 查询支付状态
+// path: 接口路径（接口短码，由平台对接时分配）
+// req: 查询请求参数
+// 返回支付状态信息，结构与支付通知一致
+func (c *Client) QueryPaymentStatus(ctx context.Context, path string, req *PaymentStatusQueryRequest) (*PaymentStatusQueryResponse, error) {
+	commonResp, err := c.doRequest(ctx, path, req)
+	if err != nil {
+		return nil, err
+	}
+
+	dataBytes, err := json.Marshal(commonResp.Data)
+	if err != nil {
+		return nil, fmt.Errorf("marshal response data: %w", err)
+	}
+
+	var paymentStatusResp PaymentStatusQueryResponse
+	if err := json.Unmarshal(dataBytes, &paymentStatusResp); err != nil {
+		return nil, fmt.Errorf("unmarshal payment status response: %w", err)
+	}
+
+	return &paymentStatusResp, nil
+}
+
+// ============================================================================
+// 回调通知处理（接口 4：支付完成通知）
+// ============================================================================
+
+// ParsePaymentNotification 从 HTTP 请求中解析支付完成通知
+// 该方法用于客户接收平台回调时使用
+func ParsePaymentNotification(r *http.Request) (*PaymentNotification, error) {
+	if r.Method != http.MethodPost {
+		return nil, fmt.Errorf("invalid HTTP method: %s, expected POST", r.Method)
+	}
+
+	body, err := io.ReadAll(r.Body)
+	if err != nil {
+		return nil, fmt.Errorf("read notification body: %w", err)
+	}
+	defer r.Body.Close()
+
+	var notification PaymentNotification
+	if err := json.Unmarshal(body, &notification); err != nil {
+		return nil, fmt.Errorf("unmarshal payment notification: %w", err)
+	}
+
+	return &notification, nil
+}
+
+// ParseGeneralNotification 从 HTTP 请求中解析通用通知
+func ParseGeneralNotification(r *http.Request) (*GeneralNotification, error) {
+	if r.Method != http.MethodPost {
+		return nil, fmt.Errorf("invalid HTTP method: %s, expected POST", r.Method)
+	}
+
+	body, err := io.ReadAll(r.Body)
+	if err != nil {
+		return nil, fmt.Errorf("read notification body: %w", err)
+	}
+	defer r.Body.Close()
+
+	var notification GeneralNotification
+	if err := json.Unmarshal(body, &notification); err != nil {
+		return nil, fmt.Errorf("unmarshal general notification: %w", err)
+	}
+
+	return &notification, nil
+}
+
+// VerifyNotificationSignature 验证回调通知签名
+// payload: 原始请求体
+// signature: 请求中的签名
+// secret: 客户在平台配置的验签密钥
+// 使用 HmacSHA256 算法验证
+func VerifyNotificationSignature(payload []byte, signature, secret string) bool {
+	return HmacSHA256Verify(secret, string(payload), signature)
+}
+
+// WriteNotificationResponse 写入通知响应
+// success: true 返回 "SUCCESS"，false 返回 "FAILED"
+func WriteNotificationResponse(w http.ResponseWriter, success bool) {
+	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+	if success {
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(NotificationSuccess))
+	} else {
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(NotificationFailed))
+	}
+}
\ No newline at end of file