The complex internal structure of modern architecture (especially buildings) which results in difficulty in fast and safe evacuation is a hotspot of indoor space intelligent navigation and path planning services currently. Based on the analysis of building data features and existing data resources, this article firstly explained the reason why it is better to choose estate spatial management data as the source. Then, an applicable building construction modeling method for emergency evacuation was developed as a foundation by establishing the mapping relationship between geographic entities and their topological expression. The data model uses "node" and "path" to express the spatial relationships and topology structure of building components, and each space entities (e.g., room, corridor) composing of the evacuating route were mapped into the "node" or "path" in the data model. After that, the whole process of modeling space route in buildings was addressed by two key steps: 1) the single floor route models were modeled, and were used to express the inner route of each floor; 2) the single floor route models were connected and the multi-floors route models were generated to express the inner route of whole building. Furthermore, some key methods including path extraction of corridor using Delaunay triangulation algorithm with constrained edge, fusion of room nodes (including elevator room, cubicle, etc.) into the ‘path', and three-dimensional route model construction from single floor to multi-floors, which were used to modeling space route, were illustrated in details. Finally, a prototype system was constructed and the New City Square in Long Jiang area, Nanjing was chosen as a case of study, and the whole building space was constructed according to the modeling method mentioned above. By integrating of the existing path-finding algorithm which named Dijkstra algorithm, the practicality of this modeling method is verified, which shows that the building space modeling method based on estate spatial data can well support evacuation route design.