In order to solve the problem that the traditional fixed time to collision (TTC) threshold early warning model is prone to early warning under higher speed conditions, this paper proposes a forward collision warning system that considers the speed of the vehicle. On the basis of the traditional collision time warning model, the speed factor is introduced to optimize the model to form a dynamic TTC warning model; use PreScan/Simulink co-simulation data to curve the speed factor; finally, for the emergency braking condition of the preceding vehicle, use The PreScan/Simulink software performs comparative simulation experiments on the traditional early warning model and the dynamic TTC early warning model. The results show that the early warning success rate of the fixed TTC threshold early warning model is 80.28%, and the success rate of the dynamic TTC early warning model is 96.94%, which verifies the effectiveness of the method.