When directly applying the existing fog algorithms to the traffic image, the transitional region is obvious and the color cast is serious, which can not meet the requirement of subsequent traffic sign detection. In order to solve this problem, a modified single traffic image dehazing algorithm based on dark channel prior image was proposed. Firstly, the modified mean shift algorithm was used to segment the sky region of traffic image; then the histogram equalization algorithm was used to defog the partitioned sky region, and the dark channel prior algorithm based on efficient bilateral filter was used to defog the non-sky region. At last, the final image dehazing was finished by image fusion. Experimental result shows that compared with the typical image dehazing algorithms, the proposed algorithm has better effect in transitional region of the sky, the color cast is not serious, and its processing speed is faster; the quantitative analysis result indicates that the proposed algorithm has better effect in dehazing, and can meet the requirement of subsequent traffic sign dectection system.