A mathematical model of an unbalanced rotor system located in aircraft with asymmetric rigidity and initial bending is given in this paper.The model for the maneuvering rotor can be used to study the dynamic characteristics of a rotor running with constant rotating speed,constant acceleration or deceleration,to investigate the influence of the velocity and acceleration of aircraft on the rotor dynamics,to analyze the amplitue response of a rotor and to diagnose the fault of a maneuvering rotor.