Abstract: The electrical signals of CO₂ arc welding contain plenty of welding information.The joint time-frequency analysis was used to study the electrical signals of CO₂ arc welding.The effect of analysis window selecting of short-time Fourier transform to the result of time-frequency analysis spectrum was discussed, and the conclusion that Hanning window has better time-frequency centralizing in analysis was gotten.Based on several welding currents and arc voltages in experiment, the characteristic of energy distribution and metal transfer was investigated by time-frequency analysis to get the information of short-circuiting transfer in electrical signals of CO₂ arc welding.The result of analysis in experiment shows that more information in electrical signals can be gotten by time-frequency analysis in CO₂ arc welding.This way has a good foreground in research and application.