The paper presents a two-stage power flow calculation method for the distribution network with loops. In the first stage, the meshed network is converted into a pure radial network by applying the superposition principle. Then the forward/backward sweep method is employed to attain the voltage differences across the loop switch of the radial distribution networks. In the second stage, continuously modifying the load power across the loop switch, the forward/backward sweep method is employed to attain the power flow of the radial distribution networks once again and finally tends to the global convergence. Last the iteration method is used to attain equivalent impedance of the high-voltage power grid. Simulation results on some actual distribution grids verify the astringency and accuracy of the proposed method.