Abstract: A new scanning circular laser vision sensor is designed.When the laser is projected on the weld,a light circularity is formed.The principle of 3D measure is stated,and camera calibration and structural light calibration are done.The parameters of camera and equation of structural light under camera reference frame are gained.The pictures of various welds under structural light are collected.By the characteristic of weld after image processing,welds can be identified and the coordinates of characteristic spot can be obtained.