Modeling and hovering control of a tilt-rotor UAV with tri-rotor configuration were studied.A 6-DOF nonlinear dynamic model of this tri-tilt-rotor UAV was established with Newton-Euler method,which was then simplified.On such basis,altitude and attitude controllers in hovering mode were designed respectively.The altitude controller was designed with PID control based on feedback linearization,and the attitude controller was composed of Backstepping-based PID controllers.Finally,the designed controllers were used for simulation experiment,and the experimental results show that the designed controllers can meet the system′s requirements for performance control.