A new algorithm to detect the pedestrians in expressway is proposed. In background estimation， the background automatic updates algorithms is adopted ,and for the moving object detection, background re? moval method is used. Then in color space, the skin color model is used for human face detection, after getting the face candidate area, the face shape information is used to eliminate similar movement face skin color area. The experimental results show that the proposed algorithm is feasible and its real-time performance can satisfy the video monitoring system.