based on the model of safe following distance, the design blue print of system is presented in the text . using the multiple impulses horae rotate speed sensor to measure the vehicle speed and nanometer radar to measure the distance of own vehicle to frontal vehicle, and analyzing and judging collected information by at89c51 which is the control centre of the system 本文在安全跟车模型的基础上,提出了系统方案:采用霍尔多脉冲转速传感器测量汽车的速度,毫米波雷达测量两车的距离和相对速度,利用at89c51作为信息采集单元的控制中心,对各种信息进行分析判断,当行车距离小于报警距离时启动相关的报警单元。