Abstract: A T-spline solid reconstruction algorithm based on octree subdivision and least square progressive iterative approximation(LSPIA)is proposed to solve the problem of reconstruction of T-spline solid from genus-zero boundary mesh.Firstly,this paper presents a cube-face-edge-vertex based four-layer geometry topology T-spline solid data structure and its knot vector calculation algorithm.Then,the parameterization of boundary mesh is realized to build the parametric mapping between the unit cube and the boundary mesh.The MVC parameterization method is also implemented to guarantee the injective mapping and no self-intersection property of the parameterization results.Later,the least square progressive iterative approximation of T-spline solid is implemented.The algorithm presented in this paper has been tested in the case study,which realizes the reconstruction of T-spline solid from boundary mesh.The proposed algorithm improves the efficiency of the reconstruction of T-spline solid and has the advantage in handling large amount of data.