Abstract: A variable polarity pulsed metal inert-gas control system,which adopt double inverter technology using isolated gate bipolar transistor,was developed based on TMS320F2812 digital signal processing chip.The constant current inner loop is fulfilled in the first stage inverter,and the constant voltage outer loop is performed in the second stage inverter.By using proportional integral modulation,I/O port and D/A converter,and the output parameters of welding can be easily controlled with high precision.At the same time,the welding device has lower complexity.Moreover,the welding parameters can be regulated contemporary and output current of variable polarity pulsed welding can be exactly controlled.