Abstract: Evaporation is an important component of the thermal balance and water budget at the earth surface and is subjected to both land use and climate change directly. The research on evaporation changes helps us comprehend climate change and probe into characteristics of regional water cycle. The observation data of 20 cm caliber evaporation pan and related meteorological elements were collected from 472 weather stations of China for 1957-2001. Statistical analysis shows that the pan evaporation in China as a whole has continuously decreased at a rate of 34.12 mm per decade, although the annual mean temperature has increased at a rate of 0.2 ℃ per decade. The regions with a significant drop in pan evaporation are East China, north part of Northwest China, South China, and south part of Tibet. Only a small part of regions with a rise in pan evaporation concentrates in Daxinganling and Beishan. Through analysis on variations of the dynamic term and energy term in Penman equation, separately, it is found that the drop of pan evaporation is mainly attributed to decreases in the energy term in East China and in the dynamic term in West China, respectively. Further investigation into tendencies of meteorological impacting factors and the correlation analysis between pan evaporation and the impacting factors tells us that sunshine duration and wind speed play the most important role in pan evaporation decrease. 