Path tracking is a key technology for mobile robot navigation. This paper proposes an adaptive robust second-order sliding mode controller to accomplish the tracking mission. First, kinematics and dynamics analysis of a skid-steered mobile robot is introduced. Then, a second order sliding-mode dynamic controller is designed for the tracking purpose. In order to improve the robustness and cope with the system uncertainties and disturbances, adaptive rules are utilized in this controller. The convergence of the control system is proved by the Lyapunov stability theory. At last, the effectiveness of the designed method are illustrated in the simulation result.