This experiment was conducted to study the effects of dietary protein level on nitrogen deposition and nutrient emissions of non-pregnant Yunnan semi-fine wool ewes, in order to provide a theoretical reference for non-pregnant Yunnan semi-fine wool ewes diet proportion and environmental load reduction. Fifty health non-pregnant Yunnan semi-fine wool ewes with similar body weight and at the age of 38 months were randomly divided into 5 groups with 10 ewes per group. Ewes in the 5 groups were fed diets with different proteins levels[7.60% (group 1), 9.49% (group 2), 11.29% (group 3), 11.56% (group 4) and 14.96% (group 5), respectively] and the same other nutrient levels. All the tested sheep were reared for 19 days, including 14 days of pre-test and 5 days of formal trial. During the formal trial period, five sheep were selected from each group for digestion and metabolism test. The test sheep were raised in a single cage in a metabolic cage. The feces and urine were collected continuously for 5 days, and diet samples were collected. The results showed as follows:1) dietary protein level had no significant effects on dry matter intake and fecal dry matter emission of non-pregnant Yunnan semi-fine wool ewes (P>0.05). 2) With the increase of dietary protein level, nitrogen intake was increased significantly (P<0.05 or P<0.01); nitrogen deposition rate in group 3 was significantly higher than that in group 1 (P<0.05), but there was no significant difference among other groups (P>0.05). 3) With the increase of dietary protein level, fecal nitrogen emission was gradually increased, there was no significant difference between group 2 and groups 1 and 3 (P>0.05), but there was significant difference among other groups (P<0.01); fecal calcium emission in group 3 was the lowest (5.04 g/d), which was significantly lower than that in group 5 (P<0.01); fecal phosphorus emission was gradually increased with the increase of dietary protein level, and it in group 5 was significantly higher than that in other groups (P<0.05 or P<0.01). 4) With the increase of dietary protein level, urinary nitrogen emission was gradually increased, there was no significant difference between group 2 and groups 1 and 3 (P>0.05), but there was significant difference among other groups (P<0.01); fecal calcium emission in group 3 was the lowest (1.18 g/d), and it was decreased by 0.53 and 0.78 g/d compared with groups 1 and 5, respectively; urinary phosphorus emission in group 1 was significantly lower than that in group 5 (P<0.05), but there was no significant difference among other groups (P>0.05). 5) Fecal and urinary nitrogen total emission in group 5 was significantly higher than that in other groups (P<0.01), fecal and urinary calcium total emission that in group 3 was significantly lower than that in other groups (P<0.01), and fecal and urinary phosphorus total emission in groups 1 and 2 was significantly lower than that in group 5 (P<0.01). 6) Fecal nitrogen rate was 42.06% to 72.44% and urinary nitrogen rate was 27.56% to 57.94%, the fecal nitrogen rate was gradually decreased and the urinary nitrogen rate was gradually increased with the increase of dietary protein level. No significant differences were found in fecal and urinary calcium and phosphorus rates among groups (P>0.05). By comprehensive consideration, under the condition of this experiment, when dietary protein level is 11.29%, the nitrogen deposition of non-pregnant Yunnan semi-fine wool ewes is the best, and the calcium total emission from feces and urine is the lowest. Dietary protein level within a certain range (7.06% to 11.56%) has no significant effects on phosphorus total emission from feces and urine. For non-pregnant Yunnan semi-fine wool ewes, the calcium and phosphorus emissions are mainly from feces, and the excess nitrogen was mainly discharged as urine nitrogen from urine.