[Objective] Quantifying the proportion and composition of each factor in runoff depth, quantitatively analyzing the contribution rate of underlying surface, climate and industrial and agricultural water use change to runoff change in the source area of the Yellow River, laying a foundation for ecological environment protection and water resources development in the Yellow River basin.[Methods] Based on the distributed hydrothermal coupling model WEP-ISF model, the paper analyzed the monthly mean discharge and the dynamic changes of actual evapotranspiration, soil temperature, soil water content and runoff composition in the source area of the Yellow River in different periods, and analyzed the contribution of each influencing factor to the change of runoff by using multi-factor attribution analysis method. [Results] The results showed that the WEP-ISF model could describe the hydrological process and hydrothermal process of the Yellow River source basin well. The mean absolute percentage error between the simulated soil temperature and the interpreted soil temperature was 69.78%~171.55%, and the Nash efficiency coefficient was more than 0.70. The mean absolute percentage error between simulated and interpreted values of soil surface water content is between 13.94% and 20.97%, and the Nash efficiency coefficient exceeds 0.5. Specifically, the Nash efficiency coefficient for the simulated and measured monthly average flow is 0.80, and the mean absolute percentage error is 25.85%.The Nash efficiency coefficient and the mean absolute percentage error of the simulated evapotranspiration value and the interpreted remote sensing value were 0.80 and 53.39%, respectively. The annual average of glacier, snowmelt and fall-off water flow is 0.9mm, 14.9mm and 70.5mm, accounting for 1.0%, 17.3% and 81.7% of the source runoff depth of the Yellow River, respectively. Compared with the baseline period of 1970-1990, the annual average runoff of Tangnahai decreased by 6.675 billion m3 during 1991-2021, the changes of glacier, snowmelt and water flow were 1.48mm, -3.8mm and -13.2mm, which accounted for 9.53%, -24.48% and -85.05% of the changes of runoff depth in the source area of the Yellow River, respectively.And the contribution rates of climate, underlying surface and socio-economic water use change were 96.46%, 2.49% and 1.05%, respectively. [Conclusion] Among the many factors affecting the runoff change in the source area of the Yellow River, the climate factor is the main driving factor leading to the runoff attenuation in the source area of the Yellow River, which is manifested in the trend of increasing glacier melt water flow and decreasing trend of snowmelt runoff and runoff.