The effect of addition of Fructus Ligustri Lucidi Extract (FLLE) on methane production and rumen fermentation in sheep was investigated in this study. FLLE addition levels were 0, 1, 2, 3 and 4 g/L of ruminal fluid. Ruminal fluid was removed from four sheep, mixed with phosphate buffer (1:2) and incubated (30 ml) anaerobically at 38°C for 24-h with or without FLLE. Results indicated that addition of FLLE linearly decreased methane production (p<0.05), linearly decreased ammonia concentration (p<0.05), and acetate to propionate ratio (p<0.05). Data of numbers of methanogens, fungi, ciliate and cellulolytic indicated that they were linearly decreased by addition of FLLE (p<0.05). Addition of FLLE at all dosages have no effect on rumen pH value, acetate molar concentration and butyrate molar concentration (p>0.05). Addition of FLLE linearly decreased count of F. succinogenes (p<0.05). In conclusion, these results of 24-h in vitro batch culture indicated that FLLE has the ability to inhibit methane production in the rumen, stimulate rumen fermentation and suppress fiber degrading bacteria, F. succinogenes. Abbreviations: FLLE=Fructus Ligustri Lucidi extract; IVDDM=in vitro digestibility of dry matter.