diff --git a/mmocr/models/textdet/detectors/mmdet_wrapper.py b/mmocr/models/textdet/detectors/mmdet_wrapper.py
index 1d6be8caa..49de8482c 100644
--- a/mmocr/models/textdet/detectors/mmdet_wrapper.py
+++ b/mmocr/models/textdet/detectors/mmdet_wrapper.py
@@ -138,6 +138,7 @@ def adapt_predictions(self, data: MMDET_SampleList,
                 # convert by text_repr_type
                 if self.text_repr_type == 'quad':
                     for j, poly in enumerate(filterd_polygons):
+                        poly = poly.reshape(-1, 2)
                         rect = cv2.minAreaRect(poly)
                         vertices = cv2.boxPoints(rect)
                         poly = vertices.flatten()