Abstract: Because the identifying precision of welding seam based on vision sensing is too low to meet the requirements of remote welding teaching, the welding seam identifying(WSI) system is designed based on force sensing, which mainly includes the collecting system of WSI signal, software system, the force model and WSI arithmetic.The teaching point is accurately calculated out by the sharp changes of six-dimensional force based on the WSI arithmetic. The experimental results show that the WSI speed is increased, and the precision and efficiency of the remote teaching is improved by WSI arithmetic.