With the increasingly wide application of three-dimensional technology in many related fields,it becomes more and more important to accurately acquire the target depth information.A method for acquiring underwater target depth information based on polarization is proposed.Firstly,the background region of image is divided based on dark channel prior,then the polarization of backscattered light is calculated by using the light intensity of background region.The backscattered light intensity of each pixel is calculated in combination of the light intensity and polarization,and the depth information of each channel is obtained with the light intensity attenuation formula of water body,thus acquiring the depth information of underwater target through fusion processing.The experimental results show that the proposed method can accurately acquire the depth information of underwater target with higher accuracy and efficiency than that of the method using dark channal prior.