Abstract: In recent years,many researches are focused on the uncertainties of GIS data.It can be found that most of these researches are focused on the uncertainties of spatial data while a few are on the attribute data.In this paper,the authors try to integrate the uncertainties of spatial data and attribute data to analyze some problems on the data uncertainties in Census GIS.This paper suggests considering the uncertainties of spatial data and attribute data at the same time in GIS analysis and application.On the basis of the characters of Census GIS,the authors concludes three kinds of data uncertainties in Census GIS.Then,some related contents,reasons,and the influence of these uncertainties are discussed in detail.On the basis of the data uncertainties discussed in this paper,the authors propose some methods to resolve the related problems.Accordingly,some concise formulae are used to illustrate the uncertainties and the related models.