Abstract: At present, current differential protection based on fiber optic channels is mainly used in key power lines, and distance protection and overcurrent protection are difficult to meet the rapidly increasing proportion of distributed new energy in distribution networks. 5G communication provides a new channel for current differential protection, but the data transmission and reception delay of 5G communication is inconsistent, and false synchronization will affect the performance of traditional differential protection. Therefore, based on 5G communication, methods such as comparing the ratio of current modulus values on both sides with the total action coefficient of protection, comparing the sum of current modulus values on both sides with the differential action current setting, and combining fault direction discrimination on both sides of the line are proposed to achieve the identification of faults inside and outside the line area. This method has been simulated and tested to meet the performance requirements of current differential protection in distribution networks.