A gear condition detection and analysis system based on vibration signal is designed to realize the real-time on-line detection of the abnormal state during the gear transmission process aiming at the modulation characteristic of gear fault vibration signal. With the development platform of LabVIEW, the envelope demodulation analysis module based on Hilbert was designed on the basis of the development of various program modules of gear condition monitoring. Finally, the modulation vibration signal of gear fault was demodulated and analyzed via simulation and experiment. The analysis results show the gear vibration detection system based on the envelope demodulation analysis module can accurately identify the type and position of the gear fault.