The method based on dark channel prior will cause excessive noise and halo phenomenon in the region of sky.To solve this problem, a method of adjusting the transmission rate of the sky region is proposed based on the credibility of the sky. To obtain the credibility coefficient of the corresponding position of the fog image,Changing the adjustment range of transmissivity adaptively,and using characteristic of the quadratic function to change the map of the credibility coefficient,then the hazefree image can be recovered by the atmosphere scattering model. A lot of experimental results show that the recovered image by the proposed method is clear and natural,especially in the sky region.Retaining the degree of haze remove in dense fog area and suppressing the noise and halo phenomenon in the region of sky. The improved method proposed in this paper can obtain better effect than the method based on dark channel prior in the processing of haze removal.