To study the straw biological fermentation feed on growth performance and blood indexes in mutton sheep, 48 small tailed han sheep were allocated to three dietary groups as control group（cut corn stalks）,group 1（silage maize straw） and group 2（straw biological fermentation feed）. The result showed that the average daily gain in group 2 increased more significantly higher than the control group（P＜0＜0.01）. Group 1 was significantly higher than the control group（P＜0＜0.05）. Feed to gain ratio of group 2 and group 1 reduced 26.84% and 23.42% compared with the control group（P＜0＜0.05）. Dry matter digestibility（P＜0＜0.05） of group 2 was more significantly higher than the control group（P＜0＜0.01）, and digestibility of crude fibre of group 2 was significantly higher than group 1（P＜0＜0.05）. Digestibility of CP of group 2 was significantly higher than group 1 and control group（P＜0＜0.05）. TP of group 2 was significantly higher than control group（P＜0＜0.05）. Albumin level of group 1 and group 2 were significantly higher than the control group（P＜0＜0.05）. Nitrogen level of urea of group 2 was depressed compared with group 1 and control group（P＜0＜0.05）. The results demonstrated that the straw biological fermentation feed promoted the growth of mutton sheep, increased the feed efficiency and improved the digestion and absorption function as well as immune level.