The invention relates to the field of electric power, in particular to a power distribution network island division method based on minimum load loss. The method comprises the following steps of: S1,performing a sequence from small to large according to the output of a distributed power supply at a fault moment; S2, in the distributed power supplies which are not subjected to island division, selecting a distributed power supply with the minimum capacity to perform power circle search, simplifying node information, and establishing an island division matrix; S3, selecting a node with the maximum average weight to be brought into an island, and when the node with the maximum average weight is not unique, selecting the node with the maximum accumulated load from the nodes with the maximum weight to be brought into the island; and S4, updating the information in the island division matrix I. According to the method, the topological relation incorporated into the island nodes is reset inthe original information, and the nodes cannot be accessed during power circle search after the connection relation with the upstream and downstream nodes is cleared, so that the power supply capacityof the distributed power supply can be fully utilized, and the minimum power loss of the load is achieved.