Abstract: The weld appearance detection mainly depends on simple visual observation and measurement ,its scientific nature and accuracy are affected by inspectors subjective factors. Line laser scanning method is the application of more advanced industrial in non-contact contour detection methods. Laser scans the weld appearance and weld profile can be obtained by using laser triangulation , then the shape information of the object can be obtained. Based on the above techniques, a line laser detection system was developed to detect the weld profile, which is composed of a semiconductor laser, CMOS industrial cameras, LabVIEW virtual instrument software platform. Based on LabVIEW, the programs including image acquisition, image processing system and the weld contour calculation were developed, which can obtain more accurate weld appearance contour information.