Abstract: Objective The aim is to solve the problems of low efficiency and low power density of traditional industrial arc welding power supply. Methods A high power and high power density arc welding power supply based on SiC devices is developed.The switch of this power supply uses SiC metal-oxide-semiconductor field-effect transistor (MOSFET) to improve the operating frequency of power supply, so as to reduce the volume of the magnetic components and switch losses in the power supply. At the same time, a single board design is adopted in the printed circuit board (PCB) structure arrangement of the power supply, so as to further reduce the overall volume of the power supply. The paper introduces the working principle of the power supply and gives a detailed account of the hardware design principle of the power supply. According to the characteristics requirements of power supply for arc welding process, a model of arc welding power supply with output power of 20 kW is up, open-loop and closed-loop tests are conducted. The external characteristics, overall efficiency and power density of the power supply are tested. Results The experimental results show that the power density of the proposed arc welding power supply in this paper is more than 8 times higher than that of the traditional grade arc welding power supply, and the peak efficiency can reach 88.49%. Conclusion The high power and high power density arc welding power supply based on SiC devices in the paper provides experimental data for the development and progress the arc welding field.