The　digital　Push　&　Pull　CO2　welding　system　is　proposed.　This　system　utilize　digital　power　source　controlled　by　DSP　and　CPLD　as　platform　with　the　AC　servo　push-pull　feeder　with　the　low　moment　of　inertia,　fast　response,　and　steady　feed　speed.　The　constant　feeding　part　combine　with　push-pull　feeding　part　to　form　the　whole　feeder　using　buffer　as　a　linker.　Consider　the　characteristics　of　the　push-pull　short-circuit　CO2　welding　technics,　the　feeder　speed　curve,　welding　voltage　and　current　waveform　control　program　was　pre-designed.　According　to　software　program,　the　steady　push-pull　CO2　welding　technics　was　achieved　with　low　spatter,　low　heat　input　and　uniform　droplet.