Load aggregator (LA) is an important measure to integrate distributed load side resources and realize “source-load” interaction, which has flexible demand side response capability. In order to take the influence of its economic dispatch on the power flow of the distribution network into consideration, a two-layer optimal dispatch of distribution network considering load aggregator is established in this paper. By performing second-order cone relaxation on the power flow equation, the original mixed integer nonlinear programming problem is transformed into a second-order cone programming (SOCP) model, which reduces the difficulty of solving the problem and improves the efficiency of the solution. The simulation results of the improved 33-node distribution network verify the feasibility and applicability of the proposed method.