In order to reduce the likelihood of secondary traffic accidents and protect the personnel who are handling the road traffic accidents, the vehicles for handing road traffic accidents should be parked in defensive positioning. After the analysis of the collision between the vehicle intruding into the road traffic accident scene and the vehicle in the defensive position, it is verified that the defensive effect of truck is obviously better than that of car and the angle parking of the defensive vehicle is also better than the parallel parking and vertical parking. On this basis, the defensive parking method of vehicles for road traffic accident scenes is presented. Based on theoretical calculation, the minimum length of the peripheral defense area is recommended for defensive parking of vehicle on all urban-road types.