Abstract: As an autonomous underwater vehicle(AUV) is a strongly nonlinear system with time-varying hydrodynamic parameters,a fuzzy sliding mode controller is presented to achieve the robust control.The switching function of variable structure control and its derivative are used as inputs of the fuzzy controller,and the derivative of variable structure control is used as outputs of the fuzzy controller.The design method of the controller offers a systematical means of constructing a set of shrinking-span and dilating-span membership functions for the controller.The contrast simulation results indicate that the proposed controller can achieve more satisfactory performance than the traditional fuzzy sliding mode controller and the quasi sliding mode controller.The controller is applied to dive plane control based on the models with hydrodynamic parameter uncertainties and input time-delay.Simulation results demonstrate the effectiveness of the controller with low energy consumption and chattering reduction.