The construction of the water vapor monitoring by ground-based GPS network in our country is still at the starting stage at present and some technology is still unripe . If there are some data in which GPS original data or the surface meteorological elements are lacked, it is unable to calculate out precipitable water vapor by GPS. It not only affects the continuous monitoring of the water variation, but also the accumulation of GPS precipitable water vapor data and the application of climatology in the future. This paper utilizes the surface meteorological data to be the relevant factors by using some methods, and the least square method to fit the experience formula of the precipitable water vapor. It can perform a substitution or a reserve scheme of the precipitable water vapor if they are lacked. This method raises the usefulness of this new observation data, keeping the continuity of GPS water vapor array, and expanding their application area, which have a very importance practical value.