Abstract: Analysing the regularity and causes of runoff evolution in changing environment is critical to the adaptive planning and management of water eco-environment and water resources. According to the natural runoff of 1956-1990 at Pingshan, Zhutuo and Chishui stations in reserve zone of the Yangtze River upstream area, the evolution characteristics and change trends of runoff and its responses to climate factors were explored by using wavelet analysis method, nonparametric Mann-Kendall trend test method and climate elasticity of streamflow. The analysis results showed that annual runoff of the three stations had a periodic similarity with an oscillation cycle of 10-14 years. At yearly and seasonal scales, runoff of the three stations showed increasing trends. At monthly scale, Pingshan and Zhutuo had a similarity with an obvious decline trend in August, whereas Chishui station had a significant increase trend in March and April. Climate elasticity of precipitation of the three stations was larger than climate elasticity of evaporation. However, the responses of annual runoff to climate factors at the three stations also had regional differences. Climate elasticity of precipitation of Pingshan and Chishui stations which flow through valley and mountain areas was larger than that of Zhutuo station; while climate elasticity of evaporation at Zhutuo station which located in Sichuan basin was slightly bigger than that of Pingshan and Chishui stations.