Abstract: Three vital angles were put forward, so the weld could be described by three-dimensional information. On this basis, mathematical model of depth recovery according to " circle-depth relation" algorithm and projection rules was constructed.The relation ship between depth values and off-axis angle γunder gas tungsten arc welding experiment condition was addressed by real experiment and the characteristic points of weld was described and located. Mean square error was used to analyze the recovery precision. The results showed:(1)Depth recovery for butt joint and ramp welded seams realized;(2)Weld can be located very well by using proposed vision sensor based on circular laser trajectory;and proposed vision sensor manifested a promising result with high precision and high efficiency.