The power output stability of a six-rotor unmanned aerial vehicle (UAV) was affected by the application environment's battery function and dynamic changes. To enhance power output stability, a design and control method of power system was proposed for a six-rotor UAV based on multi-channel dual-load dynamic output adjustment. The power input parameters of the six-rotor UAV were analyzed, and a multi-channel dual-load power matching and task scheduling model was established using multi-thread dynamic matching and compatibility modulation methods. The optimization variables were the electromagnetic torque of the UAV motor, battery material cost, output power loss, and efficiency. The adaptive optimization control of power was realized according to the task coverage radius of the UAV, which reduced the extra output overhead and improved the life cycle of the UAV. The test results show the designed UAV power system enhances the carrying capacity, reduces energy consumption, improves the balance of power output, and enhances the stability of the power output and flight life of the UAV.