Abstract: A fault detection method and device for elevator power equipment and an elevator system. The method includes acquiring running speed data of an actuator in the elevator power equipment, and using the corresponding running speed data when the elevator is at a first speed and within a preset duration as target data; obtaining time-domain signal data of acceleration by calculation according to the target data, obtaining frequency-domain signal data of acceleration by conversion according to the time-domain signal data; comparing peak frequencies that form waveform peaks in the frequency-domain signal data with characteristic frequencies of the elevator power equipment, and determining the elevator power equipment to be faulty when at least one first frequency is detected in the peak frequencies, wherein the first frequency matches one of the characteristic frequencies and the amplitude thereof exceeds a preset threshold.