With the application and development of power electronics technology, the connection of source, load, and storage to form a distribution network has gradually become a trend. The economic and technical advantages of the medium voltage DC power distribution system are significant. DC distribution protection is the key to ensure the stable and safe operation of the system, but it has not yet formed a mature technology system. This paper attempts to introduce the protection technology of the DC distribution system (DCDS) at home and abroad. First, the topology structure, converter equipment, grounding mode and transient fault characteristics of DCDS were introduced, which related to protection method formulation. Secondly, the existing protection methods of DCDS were presented, and the applicability and limitations of various protection methods were analyzed. Moreover, it also summarizes and analyzes the control and protection integration of DCDS in research and engineering practice. Finally, the protection technology of the DCDS was prospected and summarized.