Abstract: This paper introduces the impact of small hydropower grid connection on distribution network. It is pointed out that the separation of small hydropower generation and supply can fundamentally solve the overvoltage problem caused by the co-line of generation and supply. The separation of small hydropower generation and supply can effectively improve the power supply reliability of the distribution network and reduce the voltage fluctuation caused by small hydropower. The technical principle of separation of power generation and supply for small hydropower is clarified.