Micro-irregular components manufactured via rolling, extrusion, and drawing have complex shapes with irregular processing sections. This structural element is widely utilized in devices such as high-end clocks, electronics, and medical appliances. Currently, the geometric dimension measurements of micro-irregular components are realized by using a microscope during the manufacturing process. However, this method is labor intensive with low production efficiency and unstable measurement accuracy. Therefore, a line-structured light based micro-irregular component geometric dimension measurement method is proposed in this study. First, the internal and external parameters as well as the distortion coefficients of the industrial camera are obtained by implementing the calibration method by Zhang Zhengyou, while the line-structured light plane is calibrated using the Steger thinning method and least squares method. Second, a micro-irregular component geometric dimension measurement program is developed using Microsoft Foundation Classes and OpenCV. Finally, the measurement accuracy and repeatability of the method are evaluated by using the standard gauge block and the geometric dimension measurement test of three kinds of micro-irregular component. The results reveal that the overall measurement errors of this method are less than 0.1 mm in both width and height, achieving high measurement accuracy to meet the needs of actual production.