Direct Yaw-moment Control(DYC), by distributing braking forces or driving forces on wheels, generates the additional yaw-moment needed in maintaining vehicles’ driving stability, so as to improve driving stability under extreme conditions. In this paper, DYC control adopts the frequently-used Hierarchical Structure. The upper controller determines the additional yaw-moment needed in maintaining vehicles’ driving stability according to the difference between the actual yaw rate and the desired yaw rate, while the lower controller realizes the yaw-moment by controlling the wheel slip ratio. A Second Order Sliding Mode(SOSM) controller, which is designed based on the sliding mode control theory, is used as an upper controller. The input of the SOSM controller is the additional yaw-moment. The additional yaw-moment is realized by braking some of the wheels and the wheel slip ratio is regulated by the lower controller. Based the simulation environment of MATLAB/Simulink and ve-DYNA, the Hardware-In-Loop and Driver-In-Loop test platform is built, on which the DYC control strategy is evaluated. The result shows that this control algorithm can farther improve the driving stability of vehicles under extreme conditions and significantly enhance the vehicle’s active safety performance.