A new design method of sliding mode control (SMC) is proposed to generalize the conversional procedure which is usually based on Filippov’s approaching conditions for only smooth surface. As the fundamental result, the new approaching criteria are developed to show the sufficient conditions on the relation between the trajectories and a nonsmooth surface in state space, if the dynamics of the trajectories can be described by Filippov’s differential inclusion. According to the new approaching criteria, the approaching phase design of SMC can be relaxed, through the switching surface may be nonsmooth. Furthermore, for a class of nonlinear single-input single-output (SISO) systems, the sliding mode controller with a linear Lipschitz continuous switching surface can be systemically designed. From the viewpoint of SMC, it provides a new path to realize the different requirements of the sliding motion according to the partitioned regions.