A vision-based measurement ( VBM) system composed of two oppositely placed VBM units is designed to rapidly and accurately measure the coaxiality error of large-scale parts with long-span holes. The VBM unit is a line laser scanning stereo vision system, and two VBM units are used to obtain the point clouds of the end faces of the two holes. The two-point clouds are then used to calculate the centers of the circles and the normal directions on the end faces, respectively, as well as the two hole axes. The calibration method, using a specially designed target made up of four fixedly connected calibration boards whose position and orientation relations are accurately calibrated beforehand, is proposed to realize the unification of the coordinate systems of the two VBM units. These two independent axes are then merged into a common coordinate system. Finally, the coaxiality evaluation parameters are given. The accuracy verification experiment shows that the RSME of the center distance of the standard ball set with 1. 15 m span is 0. 161 mm. The proposed system is applied to measure the coaxiality of the bearing holes on both sides of the vibrating wheel of a roller, and the results are compared with those of the CMM. Results show that the deviation of the two measurement results is less than 5% , and the measurement accuracy can meet the needs of industrial production.