diff --git a/backend/services/planting-service/src/infrastructure/pdf/pdf-generator.service.ts b/backend/services/planting-service/src/infrastructure/pdf/pdf-generator.service.ts
index 3800b0d5..a72db2f5 100644
--- a/backend/services/planting-service/src/infrastructure/pdf/pdf-generator.service.ts
+++ b/backend/services/planting-service/src/infrastructure/pdf/pdf-generator.service.ts
@@ -395,8 +395,10 @@ export class PdfGeneratorService {
         const signatureImage = await pdfDoc.embedPng(signature.signatureImagePng);
 
         // 获取签名字段位置作为参考
-        let signatureX = 380; // 默认 x 坐标
-        let signatureY = 100; // 默认 y 坐标
+        let fieldX = 380; // 默认 x 坐标
+        let fieldY = 100; // 默认 y 坐标
+        let fieldWidth = 92;
+        let fieldHeight = 51;
 
         try {
           const form = pdfDoc.getForm();
@@ -404,9 +406,10 @@ export class PdfGeneratorService {
           const widgets = signatureButton.acroField.getWidgets();
           if (widgets.length > 0) {
             const rect = widgets[0].getRectangle();
-            // 使用字段左下角作为签名位置参考
-            signatureX = rect.x;
-            signatureY = rect.y;
+            fieldX = rect.x;
+            fieldY = rect.y;
+            fieldWidth = rect.width;
+            fieldHeight = rect.height;
             this.logger.log(`Signature field position: x=${rect.x}, y=${rect.y}, field size: ${rect.width}x${rect.height}`);
           }
         } catch {
@@ -433,6 +436,12 @@ export class PdfGeneratorService {
           scaledWidth = (width * maxHeight) / height;
         }
 
+        // 计算签名位置：以签名字段中心为基准，将签名图片居中放置
+        const fieldCenterX = fieldX + fieldWidth / 2;
+        const fieldCenterY = fieldY + fieldHeight / 2;
+        const signatureX = fieldCenterX - scaledWidth / 2;
+        const signatureY = fieldCenterY - scaledHeight / 2;
+
         // 在签名位置绘制图片
         lastPage.drawImage(signatureImage, {
           x: signatureX,