The Wumeng semi-fine wool sheep industry is the pillar industry in the Wumeng mountainous area. The objective of this study was to explore the effects of selenium deficiency in the environment on the mineral element metabolism and antioxidant system function in grazing Wumen semi-fine wool sheep, and provide scientific and objective data for the reference of the development of Wumen sheep industry. Samples of soil and forage were collected from affected and unaffected areas. Samples of tissue and blood were collected from affected and healthy sheep. The samples were used for hematological parameters and biochemical index analyses and mineral nutrient measurements. The results showed that concentrations of selenium (Se) in the soil and forage samples from the affected area were significantly lower than those from the unaffected area (P<0.01). The selenium concentrations of blood, liver and wool samples from the affected sheep were significantly lower than those in the healthy sheep (P<0.01). Hb, PCV and MCH of the affected sheep were significantly lower than those in the healthy sheep (P<0.01). Serum GSH-PX, CAT and T-AOC of the affected sheep were significantly lower than those in the healthy sheep (P<0.01). Serum MDA, T-NOS, NO and LPO of the affected sheep were significantly higher than those in the healthy sheep (P < 0.01). Serum AKP, CPK, LDH, ALT, AST and A/G value of the affected sheep were significantly higher than those in the healthy sheep (P<0.01). Serum total protein, albumin, α-Globulin, β-Globulin and γ-Globulin concentrations of the affected sheep were significantly lower than those in the healthy sheep (P<0.01). The study clearly demonstrated that grazing a seleniumdeficient meadow significantly reduces the selenium content of tissue and antioxidant capacity, which seriously caused oxidative damage of the Wumeng semi-fine wool sheep.