Abstract: After the large-scale access of distributed new energy to the distribution network, it is difficult to realize the rapid and accurate identification of fault section only relying on the traditional over-current protection principle. However, the multi-terminal protection principle is difficult to be popularized and applied in the distribution network due to limited communication level in distribution network. 5G communication technology has the advantage of low time delay and high reliability, so this paper carries out the longitudinal differential protection and regional topology protection of distribution network based on 5G, expanding the scope of information collection, to realize accurate fault location and isolation, and to improve the protection level and the supply reliability of distribution network. Finally, the application prospect of 5G technology in online monitoring and mobile operation and maintenance of distribution network protection is discussed. Based on the research results, this paper can provide a useful reference for the application of 5G communication in the field of distribution network relay protection.