This paper proposes a novel sliding mode control (SMC) approach for general nth order systems with matched and mismatched uncertainties and disturbances based on nonlinear disturbance observer (NDOB).By designing a novel sliding mode manifold integrated with a disturbance estimation technique,a NDOB-based SMC method is designed for these systems.As compared with the nominal SMC method,the proposed method obtains a better disturbance rejection ability in the presence of matched and mismatched uncertainties and disturbances,it can ensure a satisfactory system performance and reduce the chattering in case of reducing the switching gain.A rigorous stability analysis of the composite closed-loop system is provided using Lyapunov theory and input-to-state stable concept.Finally,two simulation results are provided to verify the effectiveness of the proposed control method.