Based on the actual measurement of precipitation and runoff data in Wenjiachuan hydrological station during the year of 1955—2013, the variation of annual, flood season and non-flood season runoff were studied by Linear trend, cumulative anomaly curve, R/S analysis. Meanwhile, the effects of precipitation and human activities on annual, flood season and none-flood season runoff variation were analyzed by M-K correlation test and double mass curve method. The results showed that: (1)the runoff of annual, flood season and non-flood season in Kuyeriver had a decreasing tendency, and this decreasing trends would continue during certain period of time in the future. (2)The stage change characteristics of annual, flood season and non-flood season runoff rise significantly in 1955—1978, decrease with the weak fluctuation in 1979—1995, and displays the significant downward trend in 1996—2013. (3)In 1979-1995, precipitation was one of the main factors to influence the runoff variation of annual and flood season, and the influence values reached to 0. 868×10⁸m³ and 0. 810×10⁸m³ respectively. In 1996-2013, human activities became the main force to affect the annual and flood season runoff decrease, and the influence values had come to 4. 622×10⁸m³and 3. 198×10⁸m³ respectively. For the non-flood season, human activities have been the dominant factor to affect the runoff change since 1979and its influence are on the increase.