In order to reduce the coupling effect between UAV and its robotic arm,and improve the stability of the quad-rotor UAV equipped with a robotic arm during flight,this article first establishes a system dynamics model,and then simplifies the model according to the actual situation.On this basis,the inner and outer loops are decomposed.The outer loop is used for controlling the position of the quad-rotor and the angle of the robotic arm,while the inner loop is for controlling the pitch angle of the quad-rotor.For the dynamic model of the outer loop,singular perturbation theory is used to decompose the outer loop variables,namely the linear velocity of the quad-rotor and the angular velocity of the robotic arm,into slow and fast subsystems,according to the velocity change characteristics,which once again reduces the coupling between the systems.For the decomposed slow and fast subsystems,non-singular terminal sliding mode control is designed and a disturbance observer is introduced to improve the stability of the armed quad-rotor UAV during flight.Finally,simulations verify the superiority of the designed algorithm.