This　paper　presents　an　integrated　simulation　for　full　digital　controlled　welding　system　for　CO2　short　circuiting　welding　using　Matlab/Simulink,　which　consists　of　power　inverter　unit,　digital　control　unit,　wire　feeder　unit　and　short　circuiting　load　unit.　This　full　digital　control　inverter　system　for　CO2　arc　welding　was　investigated　from　the　point　view　of　a　whole　part.　The　dynamic　change　processes　of　the　droplet　in　short　circuiting　period　and　arcing　period　were　considered　in　short　circuiting　load　model,　and　the　signals　of　short　circuiting　and　arcing　switching　were　determined　using　the　change　of　arc　length　and　the　theory　of　electricity　explosion,　so　the　effect　of　full　digital　control　was　directly　embodied　by　the　behavior　of　the　droplet　and　welding　arc.　The　experimental　results　validated　the　developed　simulation　model,　and　this　simulation　model　can　be　applied　to　the　research　of　digital　regulator　rules　and　dynamic　behavior　of　CO2　short　circuiting　welding　with　full　digital　controlled　system.