At present, contact tools such as plug ruler are mainly used for rail verticality detection in China. The detection accuracy and efficiency are not high, and human factors have great influence. In view of the above shortcomings, a non-contact rail scanning system is studied in this paper. The information of rail end surface is collected by rotating the laser profiler on the rotating side of the turntable to a fixed angle. Based on the principle of the dihedral angle and the data of the bottom profiler, the angle between rail end face and side, end face and bottom surface is calculated, and the relationship between rotation angle and verticality is analyzed to reduce the random error. Data fluctuation achieved vertical measurement. The experimental data show that the angle error of the system is better than ±0.2°. Compared with the results of standard measurement, the angle error is within a reasonable range, which proves that the designed system can effectively and steadily complete the rail verticality detection.