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Near real-time (NRT) water vapor remote sensing by GPS is of great potential in weather forecasting and climate research. Availability and precision of the ephemeris are the key issues. The data from the 2000 Beijing GPS/VAPOR Experiment were processed by using the precisely predicted and final ephemeris files downloaded from IGS website, and GPS PWV (precipitable water vapor) was obtained. On the basis of the radiosonde water vapor, the PWV calculated from the predicted ephemeris shows a RMS of 0.31 cm, only 0.01 cm greater than that from the final. Therefore, the predicted ephemeris can meet the requirement of GPS NRT water vapor remote sensing.