This paper has reviewed two kinds of spatio-temporal data models, namely, space based and time based ones. The authors developed an object-oriented spatio-temporal data model for planning road centerlines, and realized querying and updating of objects in the planning of road centerline. This model can make use of existent GIS functions on spatial analysis and extend functions of temporal analysis. It can preserve data and restore historical data conveniently. There exists no redundant spatial information and very little redundant temporal information. The variation reason can also be expressed with the model.