In order to solve the problem of low contrast，texture blurring and illumination uniform in the underwater images，a new visibility enhancement algorithm which is based on the underwater imaging model being different from the monochrome atmospheric scattering model is proposed in this paper. The algorithm works in the lαβ color space that has little relevance among channels. Firstly，NSCT transform is used to decompose the l channel. And then the low-frequency band is proposed based on the dark channel prior，among which the key is to design a method for estimating the intensity of light sources under non-uniform lighting condition. The directional bandpass subbands are proposed by convolution with Laplace operator. Finally，the output image is obtained through anti-NSCT transform and RGB color space convertion. The experiment using the images captured under different conditons is conducted to compare the performace of the proposed algorithm with other ones. And the results show that the proposed algorithm in this paper has good performance in eliminating nonuniform brigntness，improving contrast and sharpening the targets，and has certain advantages.