The welding seam identifying(WSI) is one of remote welding precondition. The welding seam is usually identified by vision sensor. The investigation on WSI based on force sensing is less reported. Because the interaction mechanism of friction is not clear in 6 dimension(6D) force of WSI, the influence of friction on the WSI feed and direction is studied. The experimental results show that the friction will decrease the WSI feed in XSY plane and increase in Z direction, but they is in range permitted by WSI. The friction makes WSI feed direction point to the middle of welding seam track, and do not influence WSI. Above technologies, The WSI of S groove is achieved. The average deviation of WSI is less than ±0.5mm when there is friction in 6D force of WSI. It can meet the precision of WSI in remote welding.