Abstract: The main reasons for the low voltage of the 10 kV distribution line are long power supply radius and heavy load of the line. The traditional reactive power compensation has limited effect when the peak load is heavy and the voltage is too low. And the investment of rebuilding the line is relatively large, as the construction period is long and the construction is difficult. In this paper, the mechanism of low voltage is analyzed in detail, and a battery energy storage system（BESS） solution applied to the 10 kV distribution network is proposed to solve the problem. Considering the discharge depth and efficiency, lithium iron phosphate battery is selected as the energy storage type. Based on the compensation voltage principle of BESS, the methods for calculating the rated power and capacity of BESS are put forward. In order to make full use of the energy storage capacity and the reactive power of the power conversion system（PCS）, the control strategy is also proposed. Taking a typical 10 kV radial distribution network line as an example, the simulation study is carried out. The results verified that the scheme can solve the serious low voltage problem caused by the long supply radius and heavy load, and the planning method of the rated power, capacity and control strategy of BESS are reasonable.