Abstract: The embedded Real Time Operating System (RTOS)andMicro Controller Operating System-Ⅱ (μC/OS-Ⅱ)are successfully transplanted and applied in the digital-controlled inverter arc welding power supply, which based on the dual Digital Signal Processors.For numerous affairs during welding process, after the assignment of multitasks with clear functions, scheduling of multitasks and supervising of multi-states are carried out, and the supervising on the working states of power supply in real time, and the fast and correct judgment and protection action on the faults of power supply, such as the faults of input/output model, the faults of inverter model and the faults of welding assistant equipment etc., are achieved, which guarantees the working reliability and security of welding power supply.Moreover, through the harmony and cooperation of multitasks, the friendly alternation between various working states and users are realized in real time, thus the accuracy of faults identification on power supply system and its maneuverability are improved, and the problems of digital management of real-time states of inverter arcwelding power supply and digital comprehensive management of the whole welding machine are solved.