Aiming at the limitations of dark channel and linear transformation algorithm, an iterative optimization dehazing algorithm based on improved linear transformation is proposed in this work. First, starting from the minimum color component, the adaptive linear transformation model of the atmospheric dissipation function and the minimum color component is established to obtain the initial estimation of the medium transmission rate. Then, the medium transmission rate of the bright region in the fog image is adaptively modified. Second, the high-order filter composed of Kirsch and Laplacian operators is used for iterative processing to obtain the optimal medium transmission rate. Finally, the optimized medium transmission rate and the atmospheric light value obtained by quadtree sub block search method are substituted into the atmospheric scattering model to obtain the restored image. Experimental results show that the algorithm can restore the clear and natural image, and has good dehazing effect on a single image.