Abstract: To explore effects of forage on oxidative stress and homeostasis of rumen, pH and anti-oxidative indexes of rumen, anti-oxidative indexes of serum were studied. Five Holstein cows during the dry period were used with 30 days in the first 8 periods, the last period was 3 days. Forage to concentrate ratio were 30∶70，35∶65，40∶60，45∶55，50∶50，55∶45，60∶40，70∶30，100∶0, respectively. The result indicated that rumen pH was the lowest in 100∶0 (P<0.05).The activities of SOD in the rumen was the highest in 55∶45 (P<0.05); The contents of MDA and OH·in the rumen was the lowest in 55∶45 (P<0.05); The activities of GSHPx in the rumen was the lowest in 55∶45 (P<0.05); The activities of TAOC in 55∶45 was higher than that in 30∶70，35∶65，40∶60，45∶55，50∶50，100∶0 remarkably in the rumen (P<0.05). The activities of SOD，T-AOC in the serum was the highest in 55∶45(P<0.01); The activities of GSH-Px in the serum was the lowest in 55∶45 (P<0.01); Compared with 50∶50 and 60∶40,the contents of MDA in the serum in 55∶45 had no significant difference（P＞0.05）, but was lower than that in other concentrate ratio (P<0.05); Compared with 60∶40, the contents of OH· in 55∶45 was not significantly different in the serum（P＞0.05）, but was lower than that in other concentrate ratio (P<0.05).The results indicated that forage to concentrate ratio significantly influenced the homeostasis of rumen and oxidative stress of body.