Abstract: 3D reconstruction is a classic problem in the area of computer graphics in the latest 30years.In this paper，the shortcoming and difficulties in the traditional 3D reconstruction are included and analyzed.A new strategy of 3D reconstruction is proposed： constructing the relation of all the elements by solving the expressing mode discretion，recognizing the primitive relation by solving the projection relation fuzzy，recognizing the primitive under the semantics by solving the dimension implication.At the end，the 3D reconstruction is realized on the base of primitive relation and primitive.In the primitive relation recognition，starting from the drawing and dimension integration network，the “free element” search technology is proposed to recognize the primitive relation expressed directly.Then on the basis of the primitive relation，the technology of feature vertex based on region is put up to recognize the reality of an entity and the hidden primitive relations.