Abstract: In order to improve the efficiency and accuracy of locating the weld seam of the HFW pipe,a full-auto device for detecting and locating the weld seam position and related operation method are designed. With the method the weld seam of the HFW pipe can be located and marked with a bi-color identification bar. The whole operation process is performed automatically,easily and high effectively,which provides a good idea for realization of automatic detectinglocating weld seam of the HFW pipe.