This paper provides an overview of applications of the Global Positioning System (GPS) to the active measurement of the Earth’s atmosphere. Microwave radio signals transmitted by GPS satellites are delayed by the atmosphere as they propagate to ground based GPS receivers. The zenith wet delay caused by water vapor can be transformed into an estimation of the precipitable water vapor. This transformation is achieved by multiplying the zenith wet delay by a factor whose magnitude is a function of certain constants related to the refractivity of moist air and of the weighted mean temperature of the atmosphere. Some experiments done by atmospheric scientists have showed that the GPS determined PWV by ground based GPS observation can not only significantly improve weather forecasting accuracies and numerical weather prediction models, but also contribute to the study of climate change because it represents the total latent heat available in the column from the vapor. Increased spatial and temporal resolution of PWV was proved useful in monitoring the moisture flux convergence along a dryline and the decrease in integrate water vapor associated with the passage of a midtropospheric cold front,both of which triggered severe weather over the area during the course of the experiment. So a new subject,GPS meteorology, comes into being. With the rapid growth in regional or global networks of permernant operating ground based GPS receivers, an opportunity exists to observe the distribution of water vapor with increased spatial and temporal coverage, which could prove valuable in a range of operational and research applications in the regional or global climate and short range numerical weather prediction. In this paper, we introduce the theory and the precious tests of monitoring atmosphere by ground based GPS in detail. Moreover, we present the latest development and results in this domain, such as “CLAM” and so on. We also present the situation of the development and future schemes of GPS Meteorology in Japan. With increasing of the size and scope of permanent arrays of continuously operating GPS receivers, GPS based system will soon rival the current worldwide network of approximately 600 Radiosonde launch sites. Finally, authors suggest GPS Meteorology in China need to be desired in the future.