Abstract: Water vapor content in atmosphere is important for the calculation of surface solar radiation, so it is a necessary parameter. At the same time, water vapor is a kind of climate resources which plays an important role in climatology. In order to evaluate water vapor properly, the integrated water vapor of each station is calculated based on the aerological climate standard data of the whole 124 aerological meteorological stations in China from 1971 to 2000. The distribution of annual value indicates that water vapor content in China increases with latitude except Tibetan Plateau. Using the data from China Surface Climate Standard Monthly Database (1971—2000), the surface vapor pressure is revised by corresponding surface air pressure, and then a consistent or monthly empirical formula which can be used throughout the country is obtained. Root mean square error (RMSE) of fitting value from the empirical formula and observational value is 0.25 cm. The affection of polynomial power on fitting value is discussed in depth and it can be seen that the high power polynomial which makes good fitting correlation doesn't mean the lowest RMSE. The optimal fitting formula of revised surface vapor pressure (x) by surface air pressure and integrated water vapor content (y) is: y=0.185x+0.093. The greatest advantage of this formula is that it can be used all over the country, no matter highland or lowland, in the north or in the south. Therefore, it can be considered much more close to the practical situation.