Abstract: In the manufacturing process of power plant boilers, the quality of small diameter pipe joint groove processing is the decisive factor that determines the quality of joint welds.After the automation of small diameter pipe material preparation, the consistency of groove processing quality fluctuates greatly due to the influence of tool change timeliness.Based online laser scanning technology, this article develops an online pipe fitting groove size detection system, By using SICK line laser scanner combined with precision slide rail to collect three-dimensional point cloud data of the groove, a three-dimensional point cloud analysis was designed to achieve real-time online detection of the full size of the pipe groove and trigger tool change prompts in real time, further ensuring the quality of continuous operation on the intelligent production line.