In order to solve the problems of low weld seam recognition accuracy and difficult automatic welding caused by the irregular shape of the weld seam of the surfacing free-form surface，a surface reconstruction method using the interpolation Loop surface subdivision algorithm for the three-dimensional morphological data of the surfa-cing welds collected by the rotating arc sensor was proposed． Firstly，high-quality topography data was obtained by using the Grubbs test algorithm to filter the abnormal sampling points． Then，initial triangle meshing on topography data was carried out by using local optimal Delaunay algorithm． Finally，interpolation Loop tessellation algorithm was used to tessellate the initial triangle mesh in order to rebuild the three-dimensional appearance of weld．Research result indicates that this method has good surface reconstruction effect and can reduce the error of the initial triangle meshing．Thus it has high usability．