Abstract: The factors affecting extraction yield and purity of casein were analyzed.Technical route and processing parameters were determined for extracting casein protein from milk.Fat was degreased by centrifugation at 5000 r/min for 30 min.Casein was agglutinated at pH 4.6 after being preheated to 55 ℃.Whey was removed by centrifugation at 3000 r/min for 15 min.Casein was extracted with ligarine after washing with water and drying at 50 ℃ for 3.5 h.The purity of casein protein was about 95%.