Considering the uncertain discrete-time system satisfying matched conditions, an improved disturbance compensation reaching law based sliding mode control algorithm is presented, and the dynamic features of the quasi-sliding mode are analyzed. To decrease the bandwidth of the quasi-sliding mode domain, the changing rate of the disturbance is redefined as the second-order disturbance difference. In addition, the satuation function is introduced, and by setting proper thickness of the boundary layer, the bandwidth of the quasi-sliding mode domain can achieve the magnitude of the order $O(T^3)$ without steady-state chattering, which improves the control precision of the system. Simulation results verify the effectiveness of the presented algorithm.