A control structure consisting of nonlinear feedforward and linear feedback is adopt and the optimal ascent trajectory is generated by the adjoint method.The output feedback control law and output tracking control law are designed,the conditional asymptotically stabilization is proved and optimal ascent tracking is established for the hypersonic flight vehicle.The system is separated by the observables so that the sensors are easier to be chosen.Simulation results demonstrate that the maximum energy climbing could be realized by the proposed method for the hypersonic flight vehicle and the optimal ascent trajectory could be asymptotically tracked.