Based on the vehicle risk assessment mechanism, an automatic emergency collision avoidance control strategy integrating braking and steering is designed. Firstly, considering combining vehicle safety and optimal lane change, the minimum longitudinal distance of vehicle braking and steering collision avoidance is analyzed in emergency. Then, establishing risk assessment model based on fuzzy reasoning, the vehicle collision avoidance control strategy is proposed based on the risk coefficient that reflects the risk degree of vehicle collision, and the coefficient is sent by the model. Finally, the joint simulation platform based on PreScan and MATALB/Simulink is to verify the effectiveness of the control strategy. The results show that the control strategy of single full brake based on inverse of time-to-collision（TTC^-1）cannot avoid obstacles effectively while the proposed collision avoidance control strategy is able to avoid the collision between vehicles through braking and autonomous lane changing, which improves vehicle safety.