[Objective] The effect of precipitation on runoff sequence of Hulun Lake during 1963-2014 was analyzed to provide reference for sustainable utilization and efficient configuration of river basin water resources. [Methods] Based on the observed data of Hulu Lake Station during 1963-2014, we used the methods of cumulative anomaly and Mann-Kendall to illustrate the change trend of precipitation and runoff and to demonstrate change ratio of cumulative quantity slope. We calculated quantitatively the contribution rate of the precipitation and human activities on runoff. [Results] Two inflection points occurred in 1972 and 1999. According to the two points, the cumulating process of the variables was divided into three periods, 1963-1972(T₁), 1973-1999 (T₂) and 2000-2014(T₃). Taking T₁ as the base referred period, the contribution rates of the precipitation to the decrease of runoff were 0 in T₂, and 40.7% in T₃. [Conclusion] Since the twenty-first century, the precipitation and runoff were obviously less. Annual runoff and precipitation had a good linear correlation. And the precipitation reduction was the main reason for the decrease of runoff. In recent years, population increased and animal husbandry development have their certain influence yet.