Abstract: A full digital inverted power supply based on LPC2131 ARM controller for CO₂ arc welding was developed, and the control strategy of short circuiting transfer was proposed.In this system, arc voltage is preset in accordance with the speed of a separate wire feeder, while output current during short circuiting period can be adjusted independently.The digital pulse width modulation signals are generated directly at low hardware expense, and control strategy is implemented through software algorithm.The simplified configuration shows high reliability, and control program can also be updated via upgrade interface for property enhancement.