Abstract:ECMWF can provide a wide range of grid on the vertical dimension of water vapor density, temperature, pressure and other profile data, and can also get a wide range of meteorological elements inversion. GPS could get the PWV of one single point, but the accuracy and time resolution can be very high. This article integrates the advantages of two methods of inversion to study a typical frontal rainfall in Taiwan, by detailed analysis of the changed characteristics of the meteorological elements before and after the rain. Results show that the ECMWF inversion can be used to judge whether there are the kinetics conditions for rainfall in a certain period. According to the results of GPS inversion, the forecast could be guided by higher time resolution.