Abstract:The precipitable water vapor estimated by an area GPS/MET network (GPS/PWV) has brought out the wide application prospects for improvement of detecting and forecasting severe weather and for numerical weather prediction. Some provinces and regions in China are going to build area GPS/MET networks. How to set up reasonably GPS stations within an area becomes a regardful issue. With the instance of the GPS/MET network in Yangtze River Delta area built in 2002, it is analyzed from four aspects, i.e., the moisture transmission passages, the PWV climatic statistic features, the effective radius of retrieving GPS/PWV and the influencing radius of GPS/PWV data assimilation at a station in NMP model of MM5 . Finally, some bases of reasonable distribution of GPS stations within an area GPS/MET network are discussed : more GPS stations should be located along the way of moisture transmission and the severe storm moving, the meridional density of GPS stations should be more than the zonal density; the maximum distance between the two adjacent stations is suggested to be less than 60 km, so that the effective representatives of the PWV data and its influence on the NWP may cover the whole area.