Aiming at pedestrian detection and tracking in outdoor street, an detection and tracking method based on improved YOLOv3 and SORT(Simple Online And Realtime Tracking) is proposed. Firstly, DPIOU (Distance and Proportional-IOU) loss is introduced to change the MSE (Mean Square Error) part of the original loss function to get a more accurate detection frame; secondly, the RestNet in the network structure is optimized to change the down sampling area and add the pooling layer to reduce the loss of feature information; finally, the detection results are input into SORT algorithm for modeling and matching. The results of experiment show that, compared with YOLOv3, the improved algorithm has faster convergence of loss value, AP value is 4.85 higher, and tracking accuracy rate is increased by 3.4% in the outdoor street scene. Meanwhile, the speed of the model is increased and the maximum speed is 14.39 FPS.