This study constructs the mathematical model of the unmanned aerial vehicle (UAV) operation mode for simulation model analysis by using the Unity physics engine and taking a quad-rotor UAV as the research object. Specifically, the force state of a real object is simulated by applying the force model of the UAV directly to the corresponding position of the motor, which eliminates the mathematical rigid body modeling of the model and simplifies the simulation modeling process. Additionally, the power system and control system of the UAV are modeled by analyzing the UAV motion principle, where the control system uses the PID cascade control algorithm for attitude control. Finally, the stability and validity of the UAV model are verified by flight experiments, which meet the simulation requirements of quad-rotor UAVs.