At the moving crossbeam levitation system of the gantry NC machine tool, backstepping adaptive mode control was proposed to achieve the high precision and steady levitation of the gap due to the effect of the cutting force on magnetic levitation system. Considering that the speed state variable is nonmeasurable, a state filter K was designed to estimate the parameter on line. And then the adaptive backstepping controller is designed for the nonlinear magnetic levitation system. The system can achieve the global trajectory tracking of the output because of its unique structure and the capacity to the system disturbance, while all the signals of this closed-loop system can remain bounded via the Lyapunouv theory. The simulation results show this method can keep the stability of levitation system. Meantime, this controller has powerful ability of suppressing disturbance and high rigidity.