Based on Hamiltonian energy theory, this paper proposes a pitch angle and excitation torque controller for the wind energy conversion systems (WECS), such that the closed-loop system can achieve its stability. Furthermore, in the presence of disturbances, the closed-loop system is finite-gain L2 stable by the Hamiltonian controller. The Hamiltonian energy approach provides us a physical insight and gives a new way to the controller design. The simulations are illustrated to show that the proposed method is effective.