Abstract: Based on the precipitable water vapor (PWV) retrieved from the ground-based GPS observation network in Dalian area, the characteristics of spatial distribution, diurnal variation, monthly variation and the relationship between the PWV and precipitation were analyzed. At the same time, the relationship was fitted between surface temperature and weighted average temperature according to radiosonde data from 2005 to 2011 in Dalian. The results show that the correlation coefficient between the GPS PWV and radiosonde PWV is 0.988 and the root-mean-square error is 2.5 mm. The spatial distribution of the PWV in Dalian is homogeneous. The maximum values of the PWV occur from July to August and minimum values appear in January, and their corresponding monthly averages are 40 mm and 4 mm respectively. The daily variation of the PWV is in a multiple peaks shape with 0.5 mm amplitude range in spring and winter in Dalian, while that in summer and autumn is in a single peak shape with 1.3 mm amplitude range. The PWV increases significantly 8 hours ahead of precipitation, which is of indicative role to the precipitation prediction.