diff --git a/mmpose/datasets/datasets/_base_/kpt_3d_sview_kpt_2d_dataset.py b/mmpose/datasets/datasets/_base_/kpt_3d_sview_kpt_2d_dataset.py
index c6ebde617d..ba1293f5bb 100644
--- a/mmpose/datasets/datasets/_base_/kpt_3d_sview_kpt_2d_dataset.py
+++ b/mmpose/datasets/datasets/_base_/kpt_3d_sview_kpt_2d_dataset.py
@@ -65,6 +65,7 @@ def __init__(self,
 
         self.load_config(self.data_cfg)
 
+        self.ann_info['num_joints'] = data_cfg['num_joints']
         assert self.ann_info['num_joints'] == dataset_info.keypoint_num
         self.ann_info['flip_pairs'] = dataset_info.flip_pairs
         self.ann_info['upper_body_ids'] = dataset_info.upper_body_ids