The excitation and valve control of synchronous generator is described by a multi-variable nonlinear differential-algebraic subsystem model.A stabilization controller is designed based-on backstepping control method for such systems.Firstly,if the vector relative degree exists,then the controlled systems can be decoupled and transformed equivalently by a diffeomorphism and a feedback control.Then the backstepping method is adopted for the equivalent system to design the stabilization controller,through which the whole closed-loop systems is made asymptotically stable.Finally the simulation is conducted based on MATLAB,and the results show the validity of the method proposed in this paper.