||In this paper, the Doppler effect is introduced into the communication between vehicles to detect the cars that are likely to make car crash. Besides, the behaviors and information of the coming vehicles can be promptly obtained using the Doppler effect without the need of vision. In the past, the vehicle used GPS for positioning and navigating. The information received at that time was different from the actual situation, so the target object could not be accurately located. Thus, the past GPS-based positioning can only serve as an auxiliary function and has no guarantee for the safety of the vehicle. As the fifth generation of mobile communications is about to be released, it is expected to overcome many problems, including intelligent control system and data signal time delay, which will further improve the precision positioning technology. If the vehicle is equipped with Doppler radar, it can evaluate the collision with other vehicles in advance and give the driver a warning before the collision, allowing the driver to make a clear and safe response and decision in advance. The reason why we use the Doppler radar is because vehicles can transmit information in real time, such as distance, relative speed, etc. Therefore, the purpose of this paper is to find the vehicles that have no brakes and are likely to collide with us at the intersection.