Restraint system is very important to the reduction of occupant injury risks in side impact tests. The restraint system model of the car driver side in side impact was built by using MADYMO simulation software. Considering the effect of the yielding force of pelvis energy absorber, airbag triggering time, inflator mass rate and ventilation hole size on dummy injury results, the response surfaces of occupant injury criteria were created and the reliability optimization of the occupant restraint system was carried out on the basis of Monte -Carlo stochastic simulation. The results have shown that the optimized restraint system scheme can meet the reliability design requirements.