Abstract: Climate change and human activities are important causes of runoff changes in watersheds. The Budyko hydrothermal coupled equilibrium equation is a common tool for runoff change analysis, because it takes into account certain physical causes on the one hand, and the parameters of the equation are simple on the other hand, so it has been widely used in runoff change attribution for a long time. However, the current research and application of Budyko’s formula for time-varying forms still need to be strengthened. Therefore, this paper first analyzes the trend and abrupt change of annual runoff in the study area by Mann-Kendall test and abrupt change test, and then constructs the timevarying Budyko formula based on the principle of hydrothermal coupling equilibrium, including linear, quadratic polynomial and physical mechanism, and uses Nash efficiency coefficient as the evaluation index to verify the most suitable. Finally, the contribution of precipitation, potential evapotranspiration and human activities to the runoff change is calculated, and the attribution analysis of the runoff change in the Liudong River basin is carried out. The results of this study show that the runoff of the river basin has been decreasing in recent years with the impact of climate change, with a significant change in 1997. A comparison of the sensitivity of precipitation, potential evapotranspiration and human activities to runoff show that the decrease in precipitation is the dominant factor in the decrease in runoff, with a contribution of 49%. Meanwhile, with the development of human economy and society and the construction of large water conservancy facilities, the influence of human activities on runoff changes in the basin is gradually emerging, with a contribution rate of about 26%.