Due to the impact of environment change and especial human activities, the hydrology and water resources systems appear new features. Understanding the variation rule of hydrological characteristics has important meaning to maintain sustainable development of human society. Using the analysis methods of trend,jumping and correlation, the thesis studied the variation characteristics of runoff in BeiJiang River basin based on the runoff data of 53 years in ShiJiao station from 1956 to 2008. The results show that the inter annual variation is obvious and the seasonal distribution is non uniform. Runoff has no significant ascending trend and occured one jump change in 1973. From the analysis of precipitation, evaporation and runoff coefficient ,the runoff varied at 1973. The effect of human activity on runoff evolution was analyzed based on rainfall-runoff relationship.The urbanization and soil erosion result in runoff variation in BeiJiang River basin. In conclusion, the variability of runoff in BeiJiang River basin has taken place under the influence of human activity.