On the basis analysis of the design of sliding surface, some defects of the conventional methods are stated. To overcome the defects, an improved method of variable structure control for uncertain discrete-time systems is presented. The equivalent control strategy is formed. According to the improved method, the variable structure control systems lie on the sliding surface from the beginning of any initial state, and are robust to the parameter variations and disturbance. The simulation results illustrate that the improved method is feasible.