This paper proposes a retrieval algorithm based on the binary particle swarm optimization(PSO) and the joint distribution including the distance between every two random points and the normal included angle cosine in order to improve the retrieval accuracy of 3D engineering triangular mesh model.Firstly,numerous sample points on the surface of the model are randomly chosen.Next,the distances and the cosine values of the normal angles among the sample points are calculated.Finally,a two-dimensional grid with...