Combining the observation data of water temperature at Fuxian lake, this paper explored the relationship between the water temperature and meteorological factors. Through studying the relationship between water temperature and natural environmental factors, it found that the relationship between water temperature and air temperature, relative humidity, wind speed and other meteorological factors is close, and finally established the functional equation between the three. The paper proposed a formula of estimating surface water temperature in Fuxian lake by using meteorological factors.