This paper discussed an automotive collision avoidance and warning system based on millimeter-wave radar. With the theory and application research of proactive early-warning and avoidance control, we have established the avoidance control strategy and algorithm. This system can identify dangerous targets and automatically determine whether the vehicle is in a dangerous condition. According to the level of risk status, it will take appropriate measures such as alarming, decelerating or even automatically braking to reduce the likelihood of rear-end accidents and improve driving safety on highway.