Implementations of the present application relate to a starting method and apparatus for a permanent magnet synchronous motor, a power system, and an unmanned aerial vehicle (UAV). The method includes: obtaining a current motor rotational speed and motor position information of the permanent magnet synchronous motor; determining whether the current motor rotational speed is less than a preset minimum rotational speed, and if the current motor rotational speed is less than the preset minimum rotational speed, using the preset minimum rotational speed as a feedback rotational speed; otherwise, using the current motor rotational speed as a feedback rotational speed; and performing closed-loop control on the permanent magnet synchronous motor according to the feedback rotational speed and the motor position information. In this way, the starting method is simplified and simpler. Potential failure risks in various states in the prior art are avoided, thereby effectively improving reliability of a starting process.