Abstract: Four Gansu Alpine sheep (average weight 28 kg) were fitted with permanent rumen fistulas in a 4×4 Latin square design experiment to investigate the nutritional evaluation of cotton shell and ammoniated cotton shell feed on sheep. Digestive energy, the digestibility of dry matter, nitrogen, organic matter, neutral detergent fiber, acid detergent fiber, calcium, phosphorus, N persistence of cotton shell and ammoniated cotton shell were 11.42 and 10.90 MJ/kg, 68.41% and 66.30%, 60.30% and 60.68%, 70.25% and 67.57%, 57.44% and 54.55%, 54.78% and 52.21%, 27.66% and 24.88%, 34.56% and 27.57%, 49.48% and 50.34%, respectively. After feeding cotton shell and ammoniated cotton shell to sheep, there were no significant differences in various digestion rates of nutrient digestibility. There were significant (P<0.05) differences in molar ratio of acetate, propionate, butyrate, other acids, the acetate/propionate ratio, and the concentration of protein nitrogen in ruminal fluid. There were no significant differences in pH, concentration of total volatile fatty acids, total nitrogen, or concentration of urea nitrogen. The nutrient digestibility of cotton shell and ammoniated cotton shell were not significantly different. However, an advantage of the urea ammoniated treatment was that the release of ammonia in the rumen of sheep was faster, and the microbial synthesis was of lower strength in the rumen.