In order to solve the problems of halo effect and color oversaturation in the sky region,a single image dehazing algorithm is proposed in this paper.The algorithm bases on haze line prior to estimate atmospheric optical value,and through the discrete wavelet transform construct a subband haze image model of dimension reduction,further double linear coupling term atmospheric optical transmission and distribution as a convex optimization to solve linear optimization variables for transmittance.At last,the haze free image is recovered through the atmospheric scattering model.The experimental results show that the image recovered by this algorithm is clear and natural in most cases,and the objective comparison with other commonly used image dehazing algorithms also proves the feasibility and effectiveness of this algorithm.