The study was conducted to explore the effects of dietary glutamine and L-carnitine supplementation on the alleviation of cold stress and ruminal cellulolytic bacteria of sheep, and also to provide theoretical evidence and useful reference for the application of anti-stress agent in practice. Nine healthy North East China Merino×German Mutton Merino sheep were selected and L9 (34) orthogonal design was adopted which included three glutamine levels (0, 0.6%, 1.2%) and three L-carnitine levels (0, 75, 150 mg/kg) in this experiment. The sheep were bred under low ambient temperatures (from 10 ℃ to 0 ℃), and fed different levels of glutamine and L-carnitine supplemental diets. The results were showed as follows: glutamine had a trend to decrease the relative content of Ruminococcus albus (RA) in rumen (P>0.05), L-carnitine could significantly decrease the relative content of RA in rumen (P<0.05), but glutamine combined with L-carnitine had a trend to relieve the RA decreasing; glutamine could significantly increase the relative content of Ruminococcus flavefaciens (RF) in rumen (P<0.05), L-carnitine had a trend to increase the relative content of RF in rumen (P>0.05), but glutamine combined with L-carnitine could further increase RF in rumen; glutamine and L-carnitine had a trend to decrease the relative content of Bacteroides succinogenes (BS) in rumen (P>0.05), but glutamine combined with L-carnitine had a trend to relieve the BS decreasing. The results suggest that glutamine combined with L-carnitine can relieve the relative contents of RA and BS decreasing, and further increase RF in rumen of sheep under low temperatures. It is known from the results that sheep can get effective changes of the rumen microflora and the ability to resist cold stress when fed diets supplemented with 1.2％ glutamine and 75 mg/kg L-carnitine.［Chinese Journal of Animal Nutrition，2011，23（3）：499-505］