The level of safety in the process of coal mine production is directly affected by vibration from the ranging arm in the gear transmission system of a shearer. It is thus essential to study the vibration analysis method and vibration source location technology for the ranging arm. First, the vibration signal is processed by wavelet analysis to reduce noise. Spectrum analysis is used, and the fault gear mesh frequencies are determined by the characteristic frequency amplitudes. Then, the sideband signal spectral characteristic is obtained using Morlet wavelet envelope demodulation analysis. The fault gear rotational frequencies are determined according to the amplitudes of the sideband signal spectral characteristic frequencies. Finally, the results of spectral analysis and Morlet wavelet envelope demodulation analysis are used to achieve the exact gear fault location. The vibration test and signal analysis are applied to a ranging arm in the gear transmission system of a homemade shearer. The results show that the proposed method based on wavelet analysis, spectral analysis and Morlet wavelet envelope demodulation analysis can achieve accurate location of a gear fault for the ranging arm of the shearer. It provides a method for on-site rapid fault location of a complex gear system under strong noise.