A laser displacement sensor was used to get the characteristic points by scanning each side of cubicle work-piece,and the system would generate off-line programs automatically after those points were processed by a certain software.Based on this automatic searching method,the flexible welding technology and C# language programming technology were applied to a robot welding system.The system can search the weld seam precisely,the precision and repeatability of positioning are 0.4 mm and 0.16 mm respectively.The weld system realizes the rapid searching of weld seams by the means of non-contact sensing,and reduces the searching time immensely.