The paper applies the timing linear control system theory which fits the present traffic situation in China.Then typical cross intersection is taken as an example at the Taiping north road and Zhujiang road,city of Nanjing.Based on the field investigation we analyze the whole process which could yield the signal timing method.In order to make an optimal use of time and space resources,improvement in lane canalization at intersections,optimization in signal timing is put forward.The paper applies the traffic simulation software-VISSIM to simulate the whole process,compares the optimized test with the practical survey,which obtains a good effect.