A robust Backstepping control strategy is proposed for a class of uncertain nonaffine nonlinear systems. Firstly, a global approximation method is given for uncertain nonaffine nonlinear systems, aiming to design the controller by using affine nonlinear methods. Then, a fast convergence nonlinear differentiator is designed in order to get the differential value of virtual signal and approximate unknown compound disturbances in the uncertain systems. Furthermove, the composite controller structure based on the above design is proposed, in which the robust terms and nonlinear damping term can offset the impact of the approximation errors. Finally, the simulation results show the effectiveness of the proposed method.