diff --git a/server/internal/api/exports.go b/server/internal/api/exports.go
index 8a6879f..53916e1 100644
--- a/server/internal/api/exports.go
+++ b/server/internal/api/exports.go
@@ -393,6 +393,24 @@ func (a *ExportsAPI) runJob(id uint64, db *sql.DB, q string, args []interface{},
 			}
 		}
 	}
+
+	// 检查预估行数，如果超过阈值且格式是xlsx，强制改为csv
+	if fmt == "xlsx" {
+		var rowEstimate int64
+		estRow := a.meta.QueryRow("SELECT row_estimate FROM export_jobs WHERE id=?", id)
+		_ = estRow.Scan(&rowEstimate)
+		if rowEstimate > constants.ExportThresholds.XlsxMaxRows {
+			logging.JSON("INFO", map[string]interface{}{
+				"event":        "force_csv_format",
+				"job_id":       id,
+				"row_estimate": rowEstimate,
+				"threshold":    constants.ExportThresholds.XlsxMaxRows,
+				"reason":       "row_estimate exceeds xlsx max rows, forcing csv format",
+			})
+			fmt = "csv"
+		}
+	}
+
 	rrepo.StartJob(a.meta, id)
 	if fmt == "csv" {
 		newBaseWriter := func() (exporter.RowWriter, error) {
diff --git a/server/internal/constants/constants.go b/server/internal/constants/constants.go
index 39d14f9..ebcfc4b 100644
--- a/server/internal/constants/constants.go
+++ b/server/internal/constants/constants.go
@@ -60,12 +60,15 @@ var ExportThresholds = struct {
 	ChunkThreshold int64
 	// ProgressUpdateInterval 进度更新间隔(行数)
 	ProgressUpdateInterval int64
+	// XlsxMaxRows xlsx格式最大行数，超过则强制使用csv
+	XlsxMaxRows int64
 }{
 	MaxRowsPerFile:         300000,
 	PassScoreThreshold:     60,
 	ChunkDays:              10,
 	ChunkThreshold:         50000,
 	ProgressUpdateInterval: 1000,
+	XlsxMaxRows:            100000,
 }
 
 // BatchSizes 批量处理大小配置