diff --git a/ymt_v3/client.go b/ymt_v3/client.go
new file mode 100644
index 0000000..8764cf2
--- /dev/null
+++ b/ymt_v3/client.go
@@ -0,0 +1,240 @@
+package ymt_v3
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+)
+
+// Env 环境
+type Env string
+
+const (
+	EnvTest    Env = "test"
+	EnvProduct Env = "product"
+)
+
+// 环境地址
+const (
+	testBaseURL    = "https://gateway.dev.cdlsxd.cn"
+	productBaseURL = "https://market.api.86698.cn"
+)
+
+// ClientConfig 客户端配置
+type ClientConfig struct {
+	AppID       string        // 应用ID
+	PrivateKey  string        // 应用私钥（PEM格式）
+	PublicKey   string        // 平台公钥（PEM格式）
+	Key         string        // 业务参数加密key
+	EncryptType EncryptType   // 加密类型：aes 或 sm4
+	Env         Env           // 环境：test 或 product
+	HTTPClient  *http.Client  // HTTP客户端，可选
+}
+
+// Client SDK客户端
+type Client struct {
+	config     *ClientConfig
+	httpClient *http.Client
+	baseURL    string
+}
+
+// NewClient 创建新的SDK客户端
+func NewClient(config *ClientConfig) (*Client, error) {
+	if config.AppID == "" {
+		return nil, fmt.Errorf("AppID不能为空")
+	}
+	if config.PrivateKey == "" {
+		return nil, fmt.Errorf("PrivateKey不能为空")
+	}
+	if config.PublicKey == "" {
+		return nil, fmt.Errorf("PublicKey不能为空")
+	}
+	if config.Key == "" {
+		return nil, fmt.Errorf("Key不能为空")
+	}
+	if config.EncryptType == "" {
+		config.EncryptType = EncryptTypeAES
+	}
+	if config.Env == "" {
+		config.Env = EnvTest
+	}
+
+	var baseURL string
+	switch config.Env {
+	case EnvTest:
+		baseURL = testBaseURL
+	case EnvProduct:
+		baseURL = productBaseURL
+	default:
+		return nil, fmt.Errorf("不支持的环境: %s", config.Env)
+	}
+
+	httpClient := config.HTTPClient
+	if httpClient == nil {
+		httpClient = &http.Client{}
+	}
+
+	return &Client{
+		config:     config,
+		httpClient: httpClient,
+		baseURL:    baseURL,
+	}, nil
+}
+
+// doRequest 发送请求并处理响应
+func (c *Client) doRequest(path string, bizParams interface{}, result interface{}) error {
+	// 1. 加密业务参数
+	ciphertext, err := EncryptBizParams(bizParams, []byte(c.config.Key), c.config.EncryptType)
+	if err != nil {
+		return NewSDKError("加密业务参数失败", err)
+	}
+
+	// 2. 生成时间戳
+	timestamp := GenerateTimestamp()
+
+	// 3. 构建签名字符串并签名
+	signStr := BuildSignStr(c.config.AppID, timestamp, ciphertext)
+	sign, err := SignWithRSA(signStr, c.config.PrivateKey)
+	if err != nil {
+		return NewSDKError("签名失败", err)
+	}
+
+	// 4. 构建请求体
+	reqBody := map[string]string{
+		"ciphertext": ciphertext,
+	}
+	reqBodyBytes, err := json.Marshal(reqBody)
+	if err != nil {
+		return NewSDKError("序列化请求体失败", err)
+	}
+
+	// 5. 创建HTTP请求
+	url := c.baseURL + path
+	req, err := http.NewRequest("POST", url, bytes.NewReader(reqBodyBytes))
+	if err != nil {
+		return NewSDKError("创建HTTP请求失败", err)
+	}
+
+	// 6. 设置Header
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Appid", c.config.AppID)
+	req.Header.Set("Timestamp", timestamp)
+	req.Header.Set("Sign", sign)
+
+	// 7. 发送请求
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return NewSDKError("发送HTTP请求失败", err)
+	}
+	defer resp.Body.Close()
+
+	// 8. 读取响应
+	respBody, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return NewSDKError("读取响应失败", err)
+	}
+
+	// 9. 解析公共响应
+	var commonResp CommonResponse
+	if err := json.Unmarshal(respBody, &commonResp); err != nil {
+		return NewSDKError("解析响应JSON失败", err)
+	}
+
+	// 10. 检查业务错误
+	if commonResp.Code != 200 {
+		return NewAPIError(commonResp.Code, commonResp.Message, commonResp.Reason)
+	}
+
+	// 11. 检查是否有加密数据
+	if commonResp.Data == nil || commonResp.Data.Ciphertext == "" {
+		return NewSDKError("响应中没有加密数据", nil)
+	}
+
+	// 12. 解密响应数据
+	decrypted, err := DecryptBizParams(commonResp.Data.Ciphertext, []byte(c.config.Key), c.config.EncryptType)
+	if err != nil {
+		return NewSDKError("解密响应数据失败", err)
+	}
+
+	// 13. 解析解密后的数据到结果
+	if err := json.Unmarshal(decrypted, result); err != nil {
+		return NewSDKError("解析解密后的响应数据失败", err)
+	}
+
+	return nil
+}
+
+// ==================== API方法 ====================
+
+// KeyOrder 获取券码
+// POST /openapi/v1/key/order
+func (c *Client) KeyOrder(req *KeyOrderRequest) (*KeyOrderResponse, error) {
+	result := &KeyOrderResponse{}
+	if err := c.doRequest("/openapi/v1/key/order", req, result); err != nil {
+		return nil, err
+	}
+	return result, nil
+}
+
+// KeyQuery 券码查询
+// POST /openapi/v1/key/query
+func (c *Client) KeyQuery(req *KeyQueryRequest) (*KeyOrderResponse, error) {
+	result := &KeyOrderResponse{}
+	if err := c.doRequest("/openapi/v1/key/query", req, result); err != nil {
+		return nil, err
+	}
+	return result, nil
+}
+
+// KeyDiscard 券码作废
+// POST /openapi/v1/key/discard
+func (c *Client) KeyDiscard(req *KeyDiscardRequest) (*KeyDiscardResponse, error) {
+	result := &KeyDiscardResponse{}
+	if err := c.doRequest("/openapi/v1/key/discard", req, result); err != nil {
+		return nil, err
+	}
+	return result, nil
+}
+
+// BatchOrder 批量发卡
+// POST /openapi/v1/key/batch_order
+func (c *Client) BatchOrder(req *BatchOrderRequest) (*BatchOrderResponse, error) {
+	result := &BatchOrderResponse{}
+	if err := c.doRequest("/openapi/v1/key/batch_order", req, result); err != nil {
+		return nil, err
+	}
+	return result, nil
+}
+
+// BatchQuery 批量查询
+// POST /openapi/v1/key/batch_query
+func (c *Client) BatchQuery(req *BatchQueryRequest) (*BatchQueryResponse, error) {
+	result := &BatchQueryResponse{}
+	if err := c.doRequest("/openapi/v1/key/batch_query", req, result); err != nil {
+		return nil, err
+	}
+	return result, nil
+}
+
+// VerifyNotify 验证回调通知
+func (c *Client) VerifyNotify(header *NotifyHeader, data interface{}) error {
+	return VerifyNotifySign(header, data, []byte(c.config.Key), c.config.PublicKey, c.config.EncryptType)
+}
+
+// GetBaseURL 获取当前环境的基础URL
+func (c *Client) GetBaseURL() string {
+	return c.baseURL
+}
+
+// GetAppID 获取应用ID
+func (c *Client) GetAppID() string {
+	return c.config.AppID
+}
+
+// String 返回客户端配置的字符串表示（隐藏敏感信息）
+func (c *Client) String() string {
+	return fmt.Sprintf("Client{AppID: %s, Env: %s, BaseURL: %s, EncryptType: %s}",
+		c.config.AppID, c.config.Env, c.baseURL, c.config.EncryptType)
+}
\ No newline at end of file