To improve the imaging quality of ghost imaging systems in turbid media, we propose an underwater polarization difference ghost imaging method based on histogram preprocessing. Firstly, two images in orthogonal polarization directions are acquired by polarization detection. Then, the images are preprocessed by gray-scale stretching. Finally, the reconstructed image is obtained with the polarization difference algorithm. Experimental results show that proposed method can not only improve the image quality degraded by scattering in turbid media but also enhance image details. In addition, compared with the existing polarization ghost imaging method, the gray-scale statistical analysis using the gray-scale histograms of the reconstructed images shows that when the medium has a higher turbidity concentration, the proposed method can still distinguish the target from the turbid medium.