An algorithm based on image processing to select cottonseeds was proposed. Fir stly, each position of cottonseed channels in the image was located before selec ting operation. And then, these cottonseeds were separated from the backgrounds by the difference between current image and first image, and the binary images o f cottonseeds were obtained. The number of red pixels of cottonseed regions in t he color image was calculating, and the red cottonseeds were determined. The bro ken seeds were judged by analyzing the binary image. Finally, the edge of cotton seed was extracted by differential calculus, and the exterior pixels were remove d to determine the crack seed. Experimental results indicated that the algorithm could judge the cottonseeds fast and accurately.