According to the inflow data of Huayuankou Section in recent 60 years from 1956 to 2015, such as the precipitation, measured runoff, natural runoff, total water resources volume recorded in the Master Planning of Yellow River Water Resources (1956-2000)and the Yellow River Water Resources Bulletin (2001-2015), the author analyzed the serial inflow process of 60 years and compared the average precipitation, measured runoff, natural runoff, total water resources volume above the Section in deferent year series of 1956-1979, 1956-2000, 1956-2015, 1980-2000, 1980-2015, 2001-2015. During the 60 years from 1956 to 2015, the annual precipitation above the Huayuankou Section did not change too much, among which the average precipitation in 1980 - 2000 was relatively small. While the measured runoff, natural runoff, total water resources volume in Huayuankou varied a lot in different years and reduced gradually in the long term. In recent years from 2001 to 2015, the measured runoff, natural runoff, total water resources volumes were the minimum in all the series. Since 1990, the underlying surface condition has changed greatly due to the increase of economic and social water demand, returning farmland to forest, grazing prohibition, and mining, which has become the main reason for the gradual inflow reduction in Huayuankou Section of the Yellow River.