Abstract: A split-type multifunctional underwater arc welding power supply, comprising: including a shore power supply module and an underwater power supply module is provided. The shore power supply module comprises a shore power supply main circuit unit and a shore power supply control unit. The shore power supply main circuit unit comprises an input filter circuit, an IGBT full-bridge inverter circuit, an intermediate frequency transformer, and an output rectification filter circuit. The underwater power supply module comprises an underwater power supply main circuit unit and an underwater power supply control unit. The shore power supply module is provided on the shore, and the underwater power supply module is carried underwater.