Abstract: The paper elaborates the concept of power outage loss and its influencing factors. The partition technology is introduced in the paper to segment distribution network and to determine the load point types of every block after fault outage occurs. The outage duration of every partitioned region is determined according to the load point type and the partitioned user’s power outage losses are calculated by the comprehensive user outage loss function. Finally the total users’ outage losses of the system are estimated by summary of the every partitioned user’s power outage loss. Compared with the traditional estimation method, this method is proved to be feasible and effective.