Spatial data model is the basis of three dimensional cadastre. The paper analyzes the application demands of three d imensional cadastre and proposes a hybrid three dimensional spatial data model. The model consists of two sub-models: representing sub-model and calculating-analyzing sub-model. The former is used to represent the geometrical shape of property volumes

and the latter is used to support basic computing and spatial analysis. For the integration and transformation of two sub-models

we introduce the algorithm of Constrained Delaunay Tetrahedralization and the boundary extraction algorithm of TEN. To verify the feasibility of proposed model and algorithms

several typical cases of land space right from Shenzhen are used as test data. Experimental results show that the proposed model and algorithms are effective and feasible.