In order to improve the dehazing effect of hazed image, a fast single-image dehazing method based on dark channel prior was proposed in allusion to the defect of dark channel prior rule. Based on the dark channel prior rule, the quad-tree search algorithm was adopted to estimate the value of atmospheric optical, which is used to simplify the atmospheric scattering model by the white balance. Then, the coarse estimation of medium transmission was obtained through the dark channel prior knowledge, and the guided filter and double-threshold judgment method were used to optimize the fringe and sky regions. Finally, the simplified atmospheric scattering model and tone mapping were adopted to get the dehazed image. Compared to some state-of-the-art methods, the proposed method can achieve a faster processing speed, effectively improve the definition of the dehazed image, and obtain good image color.