Abstract: On the basis of pattern recognition principle and method, an automatic recognition software for metal transfer of the metal gas are welding (MIG.MAG.CO₂)is successfully developed with Visual Basic language under the environment of Windows. A lot of spectrum of the metal transfer mode of metal gas are welding have been acquired in characteristic spectrum by testing. According to the relationship between the metal transfer type and spectrums, and geometrical pattern features of waveform of line spectrum, the data are pre-treated, several key characteristic pacameters are extracted, and the correspondent recognition function and a minimum-distance classifier have been constructed. The results show that using this system, the pattern recognition system of the metal transfer made for MIG.MAG.CO₂ welding can be done automatically. It has good accuracy and recognition precision.This software system provided the basis for controling the metal gas arc welding metal transfer automatically.