The work aims to effectively remove salt and pepper noise in color image and improve the quality of color image. A color image denoising algorithm was proposed based on HSI color space noise detection by combining salt and pepper noise detection with median filtering. The image was transformed into HSI color space, and the position of the suspicious salt and pepper noise was judged according to the characteristics of noise having maximum or minimum value in S channel. In H channel and I channel, the suspicious noise was divided into noise points and useful signals, and the detected noise pixels were denoised by median filtering. The subjective Z-score of denoising verification image was 1.30, the average PSNR was 37.54, SSIM was 0.99 and Entropy was 0.73, which was better than the commonly used algorithm in subjective and objective evaluation. The algorithm proposed can provide theoretical basis for the removal of salt and pepper noise in color images, and has certain practical value.