Abstract： The hardware of arc sound acquisition system in hyperbaric underwater MIG welding was designed, the influence of different pressure to voice signal was studied, and the microphone was calibrated according to different pressures. Based on the LabVIEW software programming, the arc sound signal, welding current and arc voltage during welding were asynchronously acquired and the signal feature of arc sound in the different pressures was analyzed both in time domain and frequency domain, which lay the foundation for the application of arc sound signal in hyperbaric underwater MIG welding quality control.