Using GPS data from six sites in Feixi, Tongcheng, Shouxian, Wuwei, Wuhu, and Chuzhou from June to July 2002, estimation was conducted on the continuous atmospheric precipitable water (PW) with a temporal resolution of 30 min. The temperature and air pressure data from above six sites were used. The accuracy of the deduced PW results is 1-2 mm, acquired by the analytical method, sufficient for weather forecasting and climate researches. The characteristics of water vapor in theses areas were analyzed by means of the results. The durative accumulation and continuous transport of water vapor are the necessary conditions of formation and development of severe storms. In order to better understand where vapor come from and what is the vapor amount, the water vapor flux was estimated in combination with NCEP data during a severe storm case.