Abstract: The paper analyzes the operation condition of vehicles under pedestrian cross-road without controlling, and adopts the queuing and fluid mechanics theory to derive delay model for vehicles under different flow conditions, the method combining qualitative and quantitative discussion is used to demonstrate the influence of pedestrians cross road on traffic flow in the conditions that the traffic fow is very small, large and very large. The study provides a basis for the setting of pedestrian crossing facilities or whether to restrict pedestrian crossing.