Aiming at the problems of color distortion, nonuniform illumination, and low contrast caused by degradation of underwater images, an underwater image enhancement method (MSFF-GAN) based on generative adversarial network was proposed. A multiscale featured fusion generator is designed, which improves the ability to use different scale features of the model and ensures that the generated image retains more detailed information. The residual dense module is constructed to solve the problem of generator characteristics extracted slower. In the discriminator, to achieve the extraction of local image features, the output matrix is discriminating so that the generated image is closer to the real image. Compared with the existing underwater image enhancement methods qualitatively and quantitatively, the proposed method has better enhancement effect on EUVP and RUIE datasets. The proposed method is superior to the contrast method of three evaluation indexes: PSNR, SSIM, and UIQM.