A　digital　control　system　of　variable　polarity　pulsed　MIG　(VPPMIG)　welding　equipment　is　developed　based　on　DSP　and　double　inverter　technology,　which　adopt　IGBT　in　this　control　system,　MCU　is　the　control　kernel　of　the　input　of　welding　parameters　and　display　system.　Control　scheme　of　welding　current　output　is　designed.　By　using　integrated　performance　of　DSP　and　real-time　data　acquisition　and　processing　of　welding　current　and　feedback　signal　of　arc　voltage,　complicated　welding　process　can　be　controlled　with　high　precision　by　using　software.　The　experiment　shows　that　this　system　can　control　the　output　waveform　of　current　and　voltage　accurately　and　maintain　the　stable　of　welding　process.