The extensive access of nonlinear loads in power systems has brought serious harmonic pollution problems. In order to maximize system reliability, reduce harmonic pollution, and optimize the economy of distributed generation, a multi-objective optimal allocation method for distributed generation considering multiple harmonic source injections is proposed in this paper. Firstly, the harmonic equivalent model is established and a reasonable harmonic power flow calculation method is selected. Then, the Multi-Objective Ant Lion Optimizer (MOALO) is used to solve the optimization model on IEEE 33 nodes. Finally, the effectiveness and feasibility of the proposed method are verified by a case study.