For a class of nonlinear systems with mismatched uncertainties, a fuzzy adaptive backstepping sliding mode control method is proposed. In the process of backstepping design, the paper utilizes the fuzzy logic system for approximating the unknown nonlinearity of the system, introduces the “differential explosion” phenomenon in requiring repeatedly the derivation of the virtual control in the backstepping method into the loworder filter, and simultaneously restrains interference with the nonmatching uncertainties. Finally, the paper designs an integral terminal sliding mode control to solve some singularity problems in the control process, speed up the convergence of the system state far away from the equilibrium position, ensure the convergence accuracy of the system and weaken the traditional sliding mode control in the presence of chattering phenomenon. Lyapunov stability analysis proves that the designed controller can ensure the finitetime convergence of closedloop system. The simulation results show that the system state tracking is good in effect and the control input chattering is weakened significantly, and the method is valid.