Abstract: Mukong hydrological station is located in the middle reaches of Pianyan river,which is a tributary of the left bank in the middle reaches of Wujiang River.Due to the influence of human activities in the upper reaches,the measured runoff is smaller than the natural runoff.After the interpolation and extension of the runoff data from the Mukong hydrological station,the water consumption of drinking water for people and animals in urban areas,water consumption of power plants and water consumption of farmland irrigation in rural areas,which had a certain influence on the runoff process,were calculated by the item reduction method,and the natural runoff of the basin was obtained,and the rationality of the reduction results was analyzed.