To evaluate the effects of dietary NDF levels on apparent nutrients digestibility of mutton sheep, four 4-month-old crossbred (Small-tail Han sheep×Poll dorset) wethers were fed four iso-caloric and iso-nitrogen diets containing different NDF levels (30%, 35%, 40% and 45% of DM) with a limited feed intake in 4×4 Latin-square design. The present results showed that dietary NDF levels did not influence (P>0.05) the apparent digestibility of OM, CP and starch but the apparent digestibility of DM of the diet containing 45% NDF was significantly lower (P<0.05) than the other groups. Dietary NDF levels also did not affect (P>0.05) the apparent digestibility of NDF, ADF, cellulose and hemicellulose, but corresponding values in 30% and 45% NDF diets were lower than those in 35% and 40% NDF diets. In conclusion, dietary NDF levels had an influence on apparent nutrients digestibility of mutton sheep to some degree and the suitable level of NDF in ration of mutton sheep was 35%～40%. ［Chinese Journal of Animal Nutrition, 2010，22（1）:70-74］