A new 4WD vehicle DYC system based on the tire longitudinal forces optimization distribution was proposed to combine the advantages of DYC and the independent four-wheel-drive chassis. The modified 2DOF vehicle model was utilized to obtain the DYC target for vehicle stability. The “feedforward + feedback” DYC controller was designed with the optimal dynamical sliding mode. The tire longitudinal forces optimization distribution mode was established with the stability index combining HSRI tire model to increase the vehicle-road grip margin. The index was constraining calculated to obtain tire forces distribution results. The simulation result shows that the remaining part of the vehicle-road adhesion is increased by the optimization distribution under DYC, which means the vehicle stability potential is improved than using the general distribution method, i.e. DYC is enhanced further.