The research on fault protection technology of AC power grid in AC/DC hybrid microgrid is very mature, while the research on fault protection technology of DC microgrid is still in the development stage. Therefore, the research and development of necessary power electronics and protection devices have become a research hotspot in recent years. In this paper, a microcomputer protection device based on the TMS320F28335 chip is developed. Considering the anti-interference of field use, detailed hardware and software design is carried out. The debugging effect is good, and the low-voltage DC short-circuit fault protection function can be reliably realized.