Abstract: The variation of tropopause serves as an indicator of global scale meteorological change. Although a lot of research on tropopause has been done, it has rarely been discussed in GPS meteorology. In fact, the tropopause shows strong correlation with weighted mean temperature and precipitable water vapor (PWV). The correlations suggest that the tropopause has been the main influencing factor, except surface temperature. Yao has proposed a formula that links the weighted mean temperature and tropopause. The formula is rearranged and the approximated quadratic functional relationship between tropopause and weighted mean temperature is derived. The following works focus on discussing the abscissa of extremum and the coefficient sign of quadratic function, using radiosonde data. The sign from one of the coefficients of quadratic function is plotted in China region. Combing the map of positive-negative signs and vertex height of abscissa of extremum with the seasonal changes of tropopause, it's easy to predict the influence of tropopause on weighted mean temperature. After discussing the relationship between tropopause and weighted mean temperature, its influence on PWV is easy to describe. The curve of PWV change will be sharp or mild when tropopause enhances or reduces the influence of surface temperature on weighted mean temperature.