Abstract:Meterological data from 20 meteorological stations during 1960-2009 were used for investigation on seasonal and interannual characteristics of pan evaporation over urban and rural areas in Beijing, and the effects of urbanization on the regional climate in Beijing were also explored. Results show that, over the past half century, the pan evaporation rate declined over the urban and rural areas, with the rate of -881 mm/10a and -760 mm/10a, respectively. Due to urbanization, the decrease in pan evaporation over the urban areas was attributed to variation of precipitation, sunshine hours, minimum temperature, diurnal temperature range and average wind speed, but over the rural areas, it was attributed to that of relative humidity, sunshine hours, air saturation deficit and average wind speed. Generally speaking, high correlationship was found among the pan evaporation and the relative humidity, sunshine hours, minimum temperature, diurnal temperature range and average wind speed in Beijing.