Aiming at a series of problems such as color distortion, low contrast, and blurred image of underwater images, this paper proposes an underwater image enhancement algorithm based on the color model, which improves the histogram linear stretching of the existing UCM algorithm, and uses the contrast limitation adaptive method to carry out nonlinear equalization of the histogram. Images processed with the proposed algorithm show a better image contrast enhancement effect, have better quality and are more in line with human visual perception. Through the construction of the underwater sea cucumber scene to simulate the experimental environment of the blue-green seabed image, 4 groups of sea cucumbers under different poses and working conditions were photographed for experiments, qualitative and quantitative analysis. It is concluded that the average values of the improved UCM algorithm under UIConM, UIQM and NIQE indexes are about 0. 63, 4. 30 and 3. 30 respectively. Compared with the other three algorithms, the image quality evaluation indexes processed by this algorithm are all optimal, which proves that the proposed algorithm has better feasibility and superiority compared with other traditional algorithms, can adapt to different underwater conditions, and has good robustness.