With the coming of 2025 in China, it is an irresistible trend to use industrial robots to process agricultural machinery online. In order to grasp workpiece intelligently, industrial robots need to identify the type of workpiece and pose of workpiece. In view of the difficulty in identifying the types of work pieces on the pipeline, an online recognition method based on the 3D point cloud of laser scanning was proposed. This method can identify which workpiece is the moving piece. First, the disordered workpiece on the assembly line was scanned, the 3D laser point cloud data of the workpiece was obtained, and the 3D laser point cloud data was initially denoised. Using MATLAB software to slice the 3D laser point cloud, the main view slicing, top view slicing, left view slicing was obtained. By using the HALCON software, the boundary information of the center slice was extracted, enhanced, segmented, and the characteristic parameters of the extracted area were extracted. Then the type of the workpiece was identified. Experimental results show that the accuracy of recognition is 96.67%. This method can be used for reference to similar problems.