Digital underwater welding power source capable of outputting multiple external characteristics and working method thereof

The invention provides a digital underwater welding power source capable of outputting multiple external characteristics and a working method thereof. The digital underwater welding power source capable of outputting multiple external characteristics comprises an EMC module, an input rectifier bridge module, an inverter module, a step-down transformer module, an output rectifier filter module, a current and voltage feedback module, an ARM microcontroller module, a PAC module, a driving module and an auxiliary power source module. According to the invention, by detecting the real-time working condition of underwater welding, the ARM microcontroller is triggered to be switched among different external characteristics such as the constant-current external characteristic, the constant-voltage external characteristic and the constant-power external characteristic in real time, and therefore it is guaranteed that the welding quality reaches the optimal effect. According to the invention, the single ARM microcontroller is adopted to replace complex analog control, the structure of a control system is simplified; and therefore, the size of the welding power source can be effectively reduced, software programming flexibility is higher, and the multi-functionality of the welding power source can be improved.