In recent years, underwater image enhancement and restoration techniques have become an important means to promote the development of underwater target detection, marine life recognition, and seabed mapping. Due to the absorption and scattering effects of water on light, underwater images often suffer from color distortion, detail blurring, and contrast reduction, which limit their applications. To address these issues, this paper proposes an underwater image enhancement algorithm based on color bias correction and multi-scale fusion. Firstly, an improved color channel compensation method is used to compensate for the attenuation of the three channels in underwater environments, and adaptive platform histogram equalization is applied to expand the distribution of the three channels, thereby correcting color bias. Secondly, the brightness channel of the image is processed separately to obtain images with improved contrast, enhanced details, and improved local overexposure and underexposure. Finally, the improved images are fused at multiple scales to obtain the final enhanced image. Experimental results show that the proposed algorithm is superior to the considered typical underwater image enhancement methods in terms of correcting color distortion, enhancing contrast, enriching details, and improving visual effects.