Abstract: In order to study the effect of varying evaporation in Weifang on the ecological environment management and rational utilization of water resources, with the data of evaporating pan as well as other meteorological observations, the author analyzed the climatic feature of evaporation and influence factors from 1961 to 2010 in Weifang by methods of linear tendency estimation and correlation coefficient. The results indicated that: the annual and seasonal evaporation showed an obvious decreasing trend in recent 50 years in Weifang. Evaporation dropped most quickly in spring, next in summer, smallest in winter. The mutation of the evaporation capacity happened in 1981, and obviously decreased afterwards. The annual evaporation capacity in Weifang was positively correlated with sunshine hours and average wind speed, which were the major reasons of the evaporation reduction in Weifang.