Robust design is an effective way to improve the reliability of structure and crash safety by considering uncertainty in vehicle design. In the traditional optimization design of vehicle body,due to ignoring of uncertainty factors,such as processing,manufacturing and environment,leading to design goals such as collision performance or lightweight effect unstable. In this paper,by considering uncertainty factors,taking side impact of a car as an example,first of all,an accurate finite element model is established and verified according to relevant crash regulations,then,after building an approximate model and a deterministic optimization model,the optimal solution is obtained by sequential quadratic programming algorithm and the reliability analysis is used,finally the original vehicle B pillar is accomplished lightweight research and improvement by using six sigma robust design method. After robust optimization design,the results are carried out a comparative analysis with the original vehicle B pillar and also with the deterministic optimization results. The analysis results show that comprehensive improvements are obtained on the robustness of collision performance after robust optimization design of vehicle B pillar,meanwhile,the quality of vehicle B pillar have reduced 3. 2% compared to the original one.