Abstract: The estimates of total zenith delay are available using Bernese GPS Software V4.2 based on GPS data every 30 s from the first measurement experiment of a ground-based GPS network in Chengdu Plain of Southwest China during the period of July to September 2004.Then estimates of 0.5 hourly precipitable water vapor(PWV) derived from global positioning system(GPS) are obtained using meteorological data from automatic weather stations.The comparison of precipitable water vapor derived from GPS and those from radiosonde observations is given at Chengdu station,with RMS(root mean square) differences of 3.09 mm.The consistency of precipitable water vapor derived from GPS to those from radiosonde is very good.It is concluded that Bevis empirical formula for estimating the weighted atmospheric mean temperature can be applicable in Chengdu areas because the relationship of GPS PWV with Bevis' formula between GPS PWV with radiosonde method shows a high correlation.The results of this GPS measurement experiment are helpful both for accumulating the study of precipitable water vapor derived from GPS in Chengdu areas located at the eastern flank of the Tibetan Plateau and for studying spatial-temporal variations of regional atmospheric water vapor through many disciplines cooperatively.