Abstract: Laser line reflection images of welding groove in various lighting conditions were taken.These lighting conditions were:darkness and fluorescent light in the night,natural light in room and under the sun light during daytime.Experiment results show that more light disturbances existed in images taken under lighting condition than that in darkness at night.But these disturbances could be cleared off by fitting up monochromatic filter and by using suitable disturbance removing methods.Information,such as width and center location of the groove and the groove clearance,could be obtained by optimization method of complex polygon.The accuracy of data collected could reach 0.125 mm and met the needs of welding tracing.