The power system of six-rotor UAV is affected by the battery function and the dynamic change of application environment, which leads to the poor stability of power output. In order to improve the stability of power output of UAV, a design and control method of power system of six-rotor UAV based on multi-channel dual-load dynamic output adjustment is proposed. The power input parameters of six-rotor UAV are analyzed. Taking the electromagnetic torque of UAV motor, battery material cost, output power loss and efficiency as optimization variables, a multi-channel dual-load power matching and task scheduling model of UAV power output is established by using multi-thread dynamic matching and compatibility modulation methods. The adaptive optimization control of power is realized according to the task coverage radius of UAV, which reduces the extra output overhead and improves the life cycle of UAV. The test results show that the designed UAV power system has improved the carrying capacity, less energy consumption and better balance of power output, and improved the stability of power output and flight life of UAV.