Aiming at the control problem of unmanned aerial vehicle system with robot arm, the corresponding coordinate system of each joint of the composite system body and operation device is established, and the transformation matrix of the points on each part of the robot arm is deduced. Considering that the operating device stays at rest most of the time and moves only when it needs to operate the object, the system is regarded as a changing static state, and the dynamics of the composite system is derived by using the Newton-Euler method. The system simulation platform of operational quadrotor aircraft based on dynamics model is built in MATLAB environment. The working interval of the operating device and the change of the center of gravity trajectory of the complex system during operation are analyzed, and the effectiveness of the control strategy to reduce the disturbance caused by the movement of the manipulator is verified by simulation experiments