In order to improve the calculation accuracy and efficiency of the weighted average temperature in precipitable water vapor, this paper uses Hong Kong as an example to design an atmospheric weighted average temperature model based on ground pressure in 2017. The model is validated by the radiosonde data from 2014 to 2016. The results show that the model has good consistency with the weighted average temperature obtained by the radiosonde data and has high precision. Based on the air pressure regression model and the air temperature regression model, the groundbased radiosonde inversion was performed in July 2017 for Hong Kong, and the inversion accuracy of the new model was verified. The results show that the model can satisfactorily meet the accuracy requirements of the groundbased inversion of precipitable water vapor, and the inversion accuracy of the regression model is better than that of the temperature regression model.