High penetration of wind power injections makes the three-phase power flow calculation of the distribution network need to consider more uncertainties, and the traditional power flow calculation methods face severe challenges. Based on the interval analysis theory, this paper describes and analyzes the uncertainty of wind power outputs using interval numbers, and establishes a three-phase interval power flow calculation model for distribution network considering the uncertainty of wind power injections. In order to solve the established three-phase interval power flow calculation model efficiently, the method of solving the mathematical model by Krawczyk-Moore operator is proposed, based on the analysis and improvement of the traditional nonlinear interval equations, and the conservativeness of the interval results can be further reduced. The feasibility of the proposed interval power flow is verified via the modified IEEE 37-node test system which is carried out based on the established dynamic simulation experimental platform, and the simulation results show that the proposed interval power flow calculation method can better track uncertainty of wind power injections than that of the existing deterministic three-phase power flow models. It can provide a reference for the upper and lower bounds of the operating state of the system for distribution network scheduling.