The invention discloses an underwater target detecting image enhancement method with contrast limited adaptive histogram equalization. The method comprises the following steps of calculating a four-directional Sobel edge detector of a gray image that corresponds with an original colorful image, a gradient image and an adaptive gain function; transforming the original color image from an RGB spaceto an HIS space through nonlinear transformation; performing enhancement processing on a brightness vector in the HIS space image by means of a contrast limited adaptive histogram equalization algorithm; transforming the enhanced HIS space image to the RGB space; performing generalized bounded multiplication operation based on an adaptive gain function on an R component, a G component and a B component in the enhanced RGB image, thereby acquiring the enhanced image based on the gradient information of the original image; performing image displaying after enhancement; and performing quantitative evaluation on the enhanced image. The underwater target detecting image enhancement method can sufficiently use the texture of the original image for realizing image enhancement processing, therebyimproving visual quality of the processed image and obtaining abundant gradient information.