A spatio-temporal data model is proposed to represent dynamic road networks based on Base State with Amendments model and object-version management theories. The network is considered to be comprised of road links and intersections, of which the evolution processes are studied respectively. Moreover, three operators on the objects: creation, deletion and update, as well as integrity constrains, are all discussed. On the basis above, a spatio-temporal data model is established and query algorithms are proposed. Database and query system are developed with the road networks data of Beijing. The status can not only be reflected, but also the historical states and evolution process can be described effectively in this model.