In order to determine the influence of road speed limit on the risk of pedestrian and bicyclist casualties in urban public transportation in China, 371 pedestrian cases and 67 bicyclist cases with estimated vehicle impact speed and detailed injury information were selected from IVAC database which had been developed via an in-depth investigation of vehicle traffic accidents. The risk models of pedestrians and bicyclists in urban traffic environment were developed by using logistic regression method and the risks of pedestrian and bicyclist casualties were quantitatively analyzed. Four correction schemes of vehicle travel speed were defined and the number of pedestrian and bicyclist casualties was estimated again based on the risk models. The results show that the fatality risks at 70 km\ub7h-1 are about 3 times of that at 50 km\ub7h-1 and 13 times of that at 30 km\ub7h-1 for both pedestrians and bicyclists. The reduction of vehicle travel speed can obviously decrease the casualty risks of both pedestrians and bicyclists. These findings can provide a foundation for setting a more reasonable speed limit for urban roads. Meanwhile, they can also provide a reference for setting speed limit for rural roads