A loop subdivision wavelet transform algorithm for the unclosed mesh surface was presented. Using the plane on which the mesh boundary located as the reflection mirror, the unclosed mesh can be mirrored as a closed one with the symmetrical structure. In this case, the boundary points of the original mesh can be treated as the inner points of the new closed mesh. After the wavelet transferred, the new unclosed mesh can be achieved by removing the "virtual mirror points" of the closed mesh. Meanwhile, the plane on which the boundary curves located of the unclosed mesh was kept unchanged during the process of the loop subdivision wavelet transformation, which brought convenient in looking for the locating surface in multiresolution-based mesh NC machining.