To promote the technology of person re-identification (Re-ID) in intelligent video analysis, a new segmentation method of keypoint-based dynamic region partitioning (KDRP) and an improved adaptive average pooling layer list network (APLNet) are proposed in this work. The KDRP addresses the limitations of traditional stripe segmentation methods avoiding the influence of shooting angles and pedestrian postures. The APLNet integrates the adaptive average pooling layer list (AAPLL) module and the priority circle loss (P-circle loss) to solve the problem of inconsistent size of feature map and promote the model performance respectively. Experimental results on different datasets have validated the effectiveness of the proposed method.