Abstarct: In this paper, dynamic sliding mode control (DSMC) is proposed to suppress the chattering which is due to the input control signal of nonlinear systems in presence of both matched and mismatched uncertainty. The performance and robustness of the closed loop system are reserved. In the other word, robust performance (invariance property) of system is reserved even in the presence of both matched and mismatched uncertainty. To counteract with mismatched uncertainty multiple sliding surfaces is defined. Moreover, in DSMC the chattering is removed due to the integrator which is placed before the input control signal of the plant. However, in DSMC the augmented system (the system plus the integrator) is one dimension bigger than the actual system and then, the plant model should be completely known. To solve this problem, a neural observer is used. One of the advantages of the proposed approach is that the upper bound of the uncertainty is not used in DSMC and observer, which is important in practical implementation. Then, a design procedure is described and simulation results are presented to demonstrate the approach.