This paper presents a study of the digital measurement of steel rods, with the objective of obtaining a laser point cloud scanning model of the rods. This is achieved by combining the scanning method of the base station and the handheld scanner, and by employing data fusion technology to generate a point cloud model of the rods with complete and local features, and with high accuracy. The paper also outlines the algorithmic principle of the PCL library. The point cloud data is processed and optimized using a variety of algorithms, including segmentation, edge extraction, and geometric feature extraction. These algorithms are employed to obtain the geometric feature values. A technical route is proposed for the digital measurement of large long steel rods for quality inspection. This route incorporates the results of finite element analysis in conjunction with the actual engineering. The geometric feature values are obtained through segmentation, edge extraction, and other point cloud algorithms. A technical route applicable to the digital measurement of long steel structure bars for quality inspection is proposed, in which the results of finite element analysis are used in combination with the actual situation of the project to correct the deformation of the bars due to the different support methods during scanning. This is done in order to improve the measurement accuracy. To enhance the precision of the measurements, the outcomes of the measurement technology were validated through a steel structure project. The findings demonstrate that the digital measurement approach exhibits superior accuracy and data processing efficiency compared to the conventional measurement method. This provides a valuable reference point for the research and practical deployment of digital measurement technology for large and long steel structure members.