[Objective] Researching the characteristics of runoff changing in the upper reaches of Bailong River in recent 50 years, and further analyzing the lagging effect of runoff to precipitation and the impacts of precipitation and human activities on runoff changes.[Methods] Based on monthly runoff observation data in Wudu hydrological station and monthly rainfall data in weather stations in the upper reaches of Bailong River basin in 1961-2010, the monthly, seasonal and annual variations of runoff in upper reaches of Bailong River basin and its tendency were analyzed using methods of concentration frequency, concentration period, Mann-Kendall test, rescaled range analysis, and so on.[Results] The annual runoff distribution in the studied area was extremely uneven. The multi-year average of runoff concentration frequency was about 34.92%; the inter-annual change of annual runoff demonstrated a decreasing trend significantly, at a rate of -3.942×10⁸ m³/10 a(p<0.001). The Hurst index was 0.98, which indicated that the decreasing trends of runoff in the studied area will continue in the future. The seasonal and monthly change of runoff also decreased significantly(p<0.05). The annual runoff dropped off abruptly in 1990 which indicated that annual runoff showed a significantly decreasing trend. There was an about 22.6 days hysteresis in the response of runoff to precipitation, and the hysteresis had slightly rising trend. The annual runoff coefficient showed that the runoff from rainfall decreased significantly(p<0.001) with the time due to plant interception, infiltration and evaporation in recent 50 years. The runoff coefficient after 1990 decreased by 0.14 as compared with the previous period.[Conclusion] Before 1990, precipitation was the dominant factors, whilst, the variations of runoff in the studied area were mainly attributed to human activities after 1990.