This study aimed at exploring the design guidelines of restraints system parameters for occupants in oblique crash under car to car collision. The full car finite element model of a compact car was used to conduct the 30° oblique impact, and the model of occupant restraint system in the driving area were established and validated. The sensitive analysis of restraint system parameters to the driver in target car and driving car was then carried out. These parameters included seat belt parameters, airbag parameters and safety seat parameters. Furthermore, restraint system parameters were optimized according to these sensitive injury parameters. It is showed that the driver’s head and chest injuries are sensitive to the locations of D-ring, anchor and buckle in the 30° oblique crash. Meanwhile, the femur forces are sensitive to the locations of anchor and buckle. Further, the driver injuries in both the target car and driving car are sensitive to airbag fire time, pretensioner fire time, airbag holes areas and mass flow rate of the airbag. After the optimization, the injury index WIC of driver of target car is induced by 33.7% and that of the driver of driving car is induced by 7.4%. The optimization results make the protecting effect of the restraint system for drivers both in target car and in driving car to be optimized.