In order to accurately diagnose gear faults, a new fault diagnosis method is proposed by combining signal empirical mode decomposition and diversity combination. First, use empirical mode decomposition to decompose the gear vibration signal to obtain several components; secondly, filter and synthesize effective components according to the kurtosis of the components and whether the kurtosis of adjacent components are close; then, use equal gain diversity combining technology Add the signal envelopes of the effective components; then, use the fast Fourier transform to obtain the envelope and the frequency spectrum of the signal; finally, perform fault diagnosis based on the frequency spectrum. The effectiveness of the method is verified by analyzing the simulation signal and the vibration signal of the gear broken tooth fault.