Tritium, as a natural environmental isotope, can be broadly applied in hydrogeology. The application of tritium is greatly limited by the scarcity observations. We have developed, selecting the International Atomic Energy Agency (IAEA) tritium data set in area from 50 S to 70 N, a modified global model for predicting the annual mean tritium concentration in atmospheric precipitation by using factor analysis method. Three random representative stations have been chosen to verify the model with direct calibrated parameters, and one station for the model with interpolated parameters. Moreover, Nanjing station has been taken as an example to explain the application of the global model. The application of factor analysis method for recovering the tritium concentration in rain has its own obvious characteristics, such as its definite meaning in physics, extensive range in application, simple process in operation, few variables in influence and well modeling the shape and peak value of the history curve. Through the analysis of the results, it shows the tritium contents in precipitation restored by the global model fit the observations very well. It also indicates that the new model is not only appropriate for the global but also improves the accuracy to some extent. In short, it provides a new idea to reconstruct the tritium concentration in atmospheric precipitation in scarcity even no data area between 1960 and 2005. However, problems of application have also been proposed, discussed and put to solutions.