According to the water level records of Dongping Lake of recent 65 years (1954-2018), Mann-Kendall mutation test and Morlet analysis were used to analyze the water level variation characteristics of Dongping Lake between 1954 and 2018, and the influencing factors of nature and human activities were discussed. The results showed that the inter-annual water levels of Dongping Lake in the past 65 years changed greatly, and the overall characteristics showed a medium-low-high variation trend, with the periodic time-scale features of 28 years and 40 years. The change of inflow runoff under the influence of human activities was the main factor of water level variations in Dongping Lake, and the climatic factors played an important role too. Due to the natural connection between Dongping Lake and the Yellow River, the water level of Dongping Lake was greatly affected by the inflow from the Yellow River and the Dawen River before 1958. Since then, the hydrological system of Dongping Lake and the Yellow River was artificially controlled, so the water level of Dongping Lake was mainly affected by the inflow from Dawen River. The water level changed accordingly after 1970, due to the increase of precipitation caused by the worsening of globalwarming. In addition, the impact of the human activities further increased after the implementation of the East Route Project of South-to-North Water Transfer in 2013.