This experiment was conducted to study the effects of treating corn stalk with probiotics in combination with lime on rumen fermentation characteristics in Northeast fine-wool sheep. Four male sheep with permanent rumen fistula were used in a 4×4 Latin square design and fed with corn stalk (group CK), corn stalk treated with 6% lime (group A), corn stalk treated with probiotics (group M), and corn stalk treated with probiotics combined with lime (group C), respectively. Rumen pH, the concentrations of ammonia nitrogen (NH3-N), microbial crude protein (MCP) and volatile fatty acids (VFAs) were determined in this experiment. The results showed that the rumen pH of animals in the four groups were all in a normal range, and the differences among the four groups were not significant (P＞0.05); the concentration of NH3-N and production of MCP in group C were significantly higher than those in group CK (P<0.05); the concentration of total volatile fatty acids (TVFAs) in group C was higher than that in the other groups at 2 and 4 h (P>0.05), but there were no significant differences in the average concentration of rumen TVFAs among the four groups (P＞0.05). The results indicate that corn stalk treated by probiotics in combination with lime is more effective to improve rumen fermentation in sheep.［Chinese Journal of Animal Nutrition，2011，23（2）：316-321］