Abstract: To improve the ability of fault handling in distribution networks, a coordinated fault isolation technique for relay protection and distribution automation was proposed. The configuration principles of relay protection and distribution automation co-processing distribution network faults is given, and the process of fault handling is analyzed. After trunk relay fault protection is acted within the specified time, distribution automation further optimizes and corrects it, so that fault isolation is in the minimum range; branch line fault relay protection can be completed, and the two do not affect each other. The static simulation system test shows that the co-operation fault isolation scheme of relay protection and distribution automation is feasible and isolates the fault area in the shortest time. Relay protection and distribution automation have significantly improved power supply reliability.