This study proposes an improved underwater polarization-difference imaging model to overcome the problem of distortion that occurs in image processing based on conventional underwater polarization-difference imaging model. By this method, the inversion process and correction parameters are introduced for the correction of target forward-scatter intensity,thereby avoiding the image distortion caused by the global parameters’ direct inversion and the negative local gray values associated with the traditional underwater polarization-difference imaging model. Using active linear-polarization illumination and underwater-target imaging detection, we obtain the polarization image data with an FD-1665 polarization imager. Using objective image-quality evaluation parameters, we compare multiple sets of experimentally processed images. Results show that the proposed model effectively improves the image-contrast value by more than 40% in comparison with those obtained by the conventional model, indicating the effectiveness of the improved polarization difference imaging model.