In order to alleviate the problems of traffic congestion at the exit of expressway, the average delay time of vehicles is used to characterize traffic efficiency, and the conflict rate to represent the traffic safety level. The model for temporary use of upstream main road shoulder at the exit of Xi Han expressway is established. Based on the speed limit theory, combined with the temporary use of the road shoulder, the traffic efficiency model and driving risk model are established by using MATLAB/ VISSIM COM software. Research results show that when the traffic volume is below 2 400 pcu/h, there is no significant difference between the driving risk and traffic efficiency when the shoulder is opened. However, when the traffic volume exceeds 2 400 pcu/h, and the speed limit is set as 80-90 km/h in the main road shoulder, the traffic efficiency is increased by 27.9% without significant differences in driving risk.