Abstract: This paper introduces the method for recognizing and deleting in terlaced triangular meshes in the triangularmesh model which is expressed based on STL files. Firstly, establishes the topology relations to the STL triangular mesh mode1; Secondly the surrounding box of mesh model is divided into certain small cube surrounding boxes, and records ID numbers of triangular meshes of this cube space that is pierced in the cube surrounding boxes; Then examines whether space of surrounding box of triangular meshes to be overlapped or not in each cube surrounding box, further determines whether two triangular meshes to be folded or not on base of spatial overlap; Finally deletes all triangular meshes and its topology relations which are symbolized interlaced triangular meshes. The example proves that this algorithm is feasible and highly effective and optimizes the quality of triangular mesh model in application of revers engineering.