Study on the quantitative response of runoff volume to climate change and human activities can not only provide a theoretical basis for the redistribution of water resources in a drainage basin,but also a policy reference for the management of water resources. This study was based on the hydrological and meteorological data series in the Xilin River Basin,a typical grassland basin,during the period from 1968 to 2015,and the Mann-Kendall trend test was used to analyze the change trend of runoff volume. The Mann-Kendall mutation test and the double-accumulation curve method were also used. The contribution rates of climate change and human activities to the change of runoff volume were quantified using the double-accumulation curve method,cumulant slope rate comparison method and elasticity analysis method. The results showed that the annual runoff volume in the Xilin River Basin was in a significant decrease trend during the period from 1968 to 2015,and its mutations occurred in 1984 and 2000 respectively. On which the period of 1968 - 1984 was regarded as the reference period,and the periods of 1985 - 2000 and 2001 - 2015 were the mutation periods. The results from the double-accumulation curve method revealed that the contribution rate of human activities to runoff volume varied in a range of 86% - 88%,which was quite different from the results obtained by other methods. The effects of both rainfall and evaporation on runoff volume were simultanously considered in the cumulant change rate comparison, so the results estimated by which and by the elasticity coefficient method were similar,and the contribution rates varied in ranges of 52. 44% - 69. 02% (1985 - 2000) and 42. 39% - 43. 64% (2001 - 2015) respectively. Holistically, the foundations and structures of different quantitative methods were different, the multiple methods were integrated in the elastic coefficient method,and this method was more reliable in quantifying the response of runoff volume in the Xilin River Basin.