Abstract:With the rapid development of urban scale in China, expressway has become the main way of travel in large cities, and the short-term surge of traffic volume in the morning and evening peak may lead to traffic congestion and other problems. The effective traffic guidance can be realized, the traffic accidents can be reduced and the delay time can be shortened by using reasonable method to predict it. According to the dispersion of traffic flow, the daily time is divided into three periods. The traffic prediction GM(1,1)and its residual models with steps of 5 min, 10 min and 15 min for each period are established by using the grey system theory. This method is applied to the short-term traffic prediction of Guangyuan Expressway in Guangzhou. The error results of various step size prediction methods in different time periods are analyzed. The adaptation time periods of model are determined by comparing the residual rate. The prediction results are compared with the traditional linear regression prediction method to verify the accuracy of the model.