1. A method for reconstructing a three dimensional (3D) model, suitable for reconstructing the 3D model of an object by using a voxel, comprising: cutting the voxel into a plurality of sub-voxels; respectively projecting the sub-voxels to a silhouette image of the object, so as to generate a projection image; when the projection image is inside the silhouette image or on an edge of the silhouette image, reserving the sub-voxel corresponding to the projection image; and determining whether to recut the sub-voxel corresponding to the projection image, which is on the edge of the silhouette, wherein when it is determined to perform the recut, the above-mentioned steps are repeated until the recut is not required, thereby reconstructing the 3D model of the object by the reserved sub-voxels.