Abstract: Rennet casein is a major raw material for making processed cheese.The research of its industrialization is still at preliminary stage in China.In this paper,its process parameters and application performance was studied.Rennet casein was prepared from the fresh skim milk with coagulant of self-prepared Mucor Pusilius rennet by the procedure of skimming,pasteurization,clotting,cooking,whey separation,washing,drying,milling and sieving.The results indicated that although the yield of rennet casein was not significantly affected by the dosage of rennet,pH of milk and cooking temperature,its functionality of melt ability,free oil,stretch ability,and oil binding capacity et al.was significantly affected by different cooking temperature.The optimized process parameters for the preparation of rennet casein is dosage of milk 1U·mL-1,clotting pH 6.6 and cooking temperature 60℃.Under this condition,the yield of rennet casein was 2.1%.