Aiming at the problems of uneven illumination of underwater image caused by supplementary illumination of deep sea and night waters,image noise,low contrast and color deviation caused by suspended particles in water,an underwater image enhancement method with nonuniform illumination is proposed.Firstly,the noise of underwater image is removed by Gaussian filter.Secondly,the maximum inter class variance (OTSU) method is used to segment the light and dark region mask of the image, divide the brightness map into light and dark regions, and homomorphic filtering is performed on the dark regions to correct the shadows caused by uneven illumination. Then,the new brightness map is obtained by fusing the light and dark areas with weighted average method,and the color image is synthesized again.Finally,the underwater image is processed with contrast limited adaptive histogram equalization (CLAHE),and gray world to enhance contrast and color distortion correction,get enhanced underwater image.The experimental consequences express that the proposed method can valid ameliorate the uneven illumination problem,remove the underwater image noise and enhance the image contrast,which is conducive to the subsequent target detection,tracking and other tasks.