This paper presents a method of power flow calculation for low voltage distribution network including pump loads. By combining torque balancing equations of induction motors in pump loads and power balance equations of each node in distribution network, the low-voltage distribution network power flow calculation model including pump load characteristics is constituted. Based on the Newton-Raphson algorithm of solving the distribution network power flow calculation, two methods of uniform iteration and alternating iteration of pump load motor torque balance equations with each node power balance equations are proposed to solve the problem. The numerical results of real low voltage distribution networks show that the proposed method can obtain load nodes voltage more accurately, and it can get the node voltage of pump loads during normal operation and startup.