Tilt rotor unmanned aerial vehicle (TRUAV) is a transformable aircraft with abilities of hovering and high-speed cruise. Its transition control is still a difficult point due to varying structure and dynamic behaviour. The main contribution of this paper is to put forward a transition control method based on backstepping for a quad-TRUAV, and fault tolerant control is researched to keep its cruise ability under rotor-tilt axle stuck fault. Explicit mode transition would be avoided by regarding rotor-tilt angle as a control input generated from decoupling with virtual control variables. Numerical results in transition procedure and facing rotor-tilt axle faults are provided to illustrate control effectiveness.