Imaging in the atmosphere presents the phenomenons of low contrast,lo w saturation and hue offset due to atmospheric particles such as haze and fog.Th e dehaze image based on dark channel prior presents the phenomena of halo effect and color distortion in sky region.In view of the characteristics of color dist ortion,detail and edge blur of pictures taken underwater,an underwater image e nhancement algorithm based on color attenuation prior was proposed.First,when calculated the dark channel function,the minimum value filter was used to denoi se.Minimum value filtering is a relatively conservative image processing method ,which can be simply filtered.Then,the image was processed for saliency map, and the depth estimation was completed using the color prior rule.This filterin g method could not only reduce noise,but also prevented color distortion.Final ly,the simplified atmospheric scattering model and tone mapping are used to get the restored image.It corrected by gamma transformation to achieve flexible def ogging.Experimental results show that compared with several typical underwater image defogging algorithms,the algorithm in this paper can improve the clarity and contrast of the image,and at the same time obtain better image color.