This application relates to a motor controller applied to an electric vehicle, a microprocessor in the motor controller, and a sampling trigger method applied to the microprocessor. The sampling trigger method includes: a signal generation module generates an exciting fundamental wave signal to drive the resolver to work; a signal processing module determines an exciting symbol based on the exciting fundamental wave signal, where the exciting symbol includes alternate high-level signals and low-level signals, and the signal processing module further determines a zero crossing point signal of the exciting fundamental wave signal based on the exciting symbol; and a phase shift processing module performs phase shift processing on the zero crossing point signal to obtain a sampling trigger signal, to trigger the microprocessor to sample the resolver feedback signal. In this solution, fewer peripheral circuits of a chip are used, thereby improving a product integration degree.