To evaluate feed characteristics and nutritional value of cotton stalk and cotton stalk diet, and mutton safety of sheep fed the cotton stalk diet, this study was carried out to investigate effects of cotton stalk parts ratio, approximate nutrients, overall digestibility, free intake, digestion and metabolism of the cotton stalk on growth and slaughter performance, and mutton safety of sheep fed the cotton stalk diet. In experiment 1, the cotton stalk parts ratio and approximate nutrients in cotton stalk were determined. In experiment 2, the apparent digestibility of cotton stalk in sheep was estimated by difference method under restricted feeding. In experiment 3, a corn stalk diet as a control, the digestion and metabolism of cotton stalk diet for sheep was evaluated by self control design. In experiment 4, 120 days of feeding experiment was conducted to study on the effects of the growth and slaughter performance of sheep fed the corn stalk diet and the cotton stalk diet, and the contents of free gossypol and main pesticide residues in sheep tissue samples were determined. The results showed as follows:1) the ratios of main stem, branches, leaves and cotton boll shell of cotton stalk were 31.48%, 10.99%, 17.12% and 40.41%, respectively. The contents of organic matter, crude protein, cellulose, hemi-cellulose and lignin of cotton stalk were 90.03%, 6.41%, 34.76%, 15.58% and 10.29%, respectively. 2) The apparent digestibility of dry matter, organic matter, crude protein, cellulose, hemi-cellulose, energy, calcium and phosphorus of cotton stalk for sheep were 38.24%, 37.99%, 1.58%, 60.50%, 58.13%, 44.05%, 57.76% and 45.00%, respectively. The digestible energy of cotton stalk was 10.28 MJ/kg DM. 3) Compared with the corn stalk diet, the apparent digestibility of organic matter, cellulose, energy of sheep fed the cotton stalk diet were lower by 5.30% (P<0.05), 10.04% (P<0.05) and 13.63% (P<0.01), respectively, but the apparent digestibility of calcium and phosphorus were, respectively significantly increased (P<0.01), while there was no significant difference (P>0.05) in the free intake and digestibility, and as well no significant difference (P>0.05) in daily body weight gain, carcass weight and carcass lean weight. 4) The content of free gossypol and the main pesticide residues in the tissue samples of sheep was not detected. This study shows that the sum of cotton boll shell, branches, and leaves is approximately 70%, and it has a large amount of available resources in the 3 parts of the cotton stalk; cotton stalk is a roughage with higher content of lignin and lower apparent digestibility of crude protein (suggested as zero in practice), and its energy is lower, but the calcium and phosphorus nutrition contents are higher than corn stalk; there is no significant difference in the weight gain and slaughter performance of sheep between the cotton stalk diet group and corn stalk diet group, and the feeding effect is similar; free gossypol and main pesticide residues in tissue samples of sheep fed the cotton stalk diet are not detected, the food security is not affected.