In this paper, a novel extension controller based on the scheme of sliding mode control is investigated. The control strategy of the proposed controller is divided into two parts. One part is the equivalent control of sliding mode control. It can be directly obtained from the known nominal system. The other part is the well-known robust control. This control term is used to compensate the system uncertainty and external disturbance. By integrating the essential concept of extension set theory with the sliding mode control , the robust extension controller can be easily realized. In this study, a basic extension controller is organized first without any specific expert knowledge about the controlled system. The extension dependent functions are employed to provide system states´ information under control. A set of parameter is incorporated in the extension controller so that a robust control, also called as a hitting control, is established to guarantee the system robust stability. Actually, the proposed extension controller is stable in the sense of the Lyapunov. Finally, the proposed extension controller is applied to controlling a nonlinear system to verify its effectiveness and ability.