Given the shortcomings of the three-phase power flow calculation method for the distribution network, a new three-phase power flow hybrid calculation method for a distribution network with distributed power supply is proposed. This paper first analyzes the characteristics of the relevant components, and establishes the three-phase mathematical model of distribution lines, distribution transformers and loads. Analyzing the processing methods of four different types of distributed power supply nodes, a three-phase power flow calculation model is established using a forward-backward algorithm and the Newton-Laphson method. The loop impedance matrix method is used to calculate the three-phase voltage difference. It solves the applicability problem of the single-phase power flow calculation. The convergence of the node voltage is used to control the power flow calculation. The voltage value can be obtained directly, and the iterative calculation is simple and efficient. Finally, it is verified that this method has good convergence by taking the IEEE 33-node network model and a 10 kV distribution line from Shantan substation as examples. This work is supported by National Natural Science Foundation of China (No. 51777079).