Abstract: Due to the influence of complex imaging environment, there exist many problems in the underwater images acquired by optical vision system, such as low contrast, blur and color distortion. To solve this problem, an image restoration algorithm based on the modified scattering model is proposed. Firstly, the absorption attenuation characteristics of light in water are analyzed in depth, and based on the simplified atmospheric scattering model, the background light of water body is incorporated into the direct attenuation term of the model. Secondly, the inverse channel of red channel is used to compensate for the rapid attenuation of red light. Then, the background light value of water body is estimated by the hierarchical search algorithm based on quadtree. Finally, the medium transmittance is estimated on the basis of the modified imaging model by combining the underwater dark channel prior, and the underwater image is restored. The experimental results show that the restored underwater image displays natural color and can effectively restore the details of the far scene in image. The comprehensive evaluation index of image contrast, color and saturation is better than the contrast algorithm, and the proposed algorithm is suitable for different types of underwater degraded images.