In order to realize network-based line loss management and solve the problem that the traditional loss reduction measures are difficult to meet the line loss rate requirements under the condition of high energy consumption and low power, this paper proposes an optimal combination model of distribution network lines. By expounding the application scenarios and problems of the line loss electric quantity optimization distribution method in the line loss management, an optimal combination model of the line is constructed. Then, with aiming at maximizing the number of lines whose line loss rate meets the assessment requirements and taking the line loss rate evaluation standard as the constraint condition, the combination optimization algorithm is proposed and the problem is sloved. The results of the example show that the model can effectively determine the transfer direction of the high-loss load of the distribution network, providing a reliable basis for subsequent network reconstruction and network planning.