Based on the traditional line-structured light measurement technology, we proposed a line-structured light imaging method of rail profile based on polarization fusion. First, the polarization component images and total intensity images of rail laser section at multiple angles were obtained by using a polarization camera. Furthermore, combining the correlation and complementarity of light strip information in the polarization component images and total intensity images, we constructed an image fusion algorithm based on the evaluation of light strip reliability, which improved the image quality of rail laser section. In addition, the experimental demonstration using the polished rails indicated that in the fused images of polarization component images and total intensity images, there was no longer local overexposure of light strip and the quality of light strip was improved. In comparison with the traditional method, the maximum measurement error of rail profile in the overexposed area was reduced from 0.31 mm to 0.10 mm, effectively improving the accuracy of rail profile detection.