Abstract: Because of strong nonlinear characteristics, modeling uncertainties and complicated flight environment, the control of hypersonic flight vehicle becomes a challenge. An approach which combines feedback linearization and adaptive control for a multiple-input-multiple-output(MIMO) nonlinear system with parameter uncertainty was proposed. Feedback linearization was used to obtain the linear input-output dynamics and a feedback controller was designed. The uncertain parameters were estimated online by an adaptive control law and the Lyapunov method was introduced to analyse the close-loop system stability. For the conditions of choosing different outputs, a discussion was made on how to remove the inner dynamics to avoid unexpected unstable dynamics. A hypersonic cruise flight vehicle longitude model was used to testify the reliability of the proposed approach. In order to control altitude and velocity channel, a feedback controller with adaptive online estimator was designed for the parameter uncertainties in vehicle model and atmosphere model. The simulation was operated to track the altitude and velocity step commands. Results show the controller has good tracking performance with rapid converge speed.