Due to the fracture, tilt, and deformation of railway freight train number and characters, the traditional segmentation method faces the problem of low segmentation accuracy. In this paper, a segmentation method based on improved enclosing circle was proposed. Firstly, the adaptive run length algorithm was used to segment the double line train number and characters based on the single line and double line arrangement of railway freight trains. With the characteristics of foreground processing of background pixels in run length algorithm, the run length algorithm was used to remove the breaks in advance, and then the enclosing circle method was used for character segmentation. The experimental results show that, in the case of low image quality, the proposed method can achieve good segmentation accuracy. Compared with the traditional algorithms, it is superior in segmentation accuracy and robustness.