Abstract: The effects of Impatiens balsamina preparations, including ethanol extracts and plant solid powder (0.5%, 1.0% and 2.5%), on methane production and metabolic parameters of cattle rumen microorganisms were studied in vitro. Forages with straw 0.90 g, corn 0.45 g and soybean 0.15 g (1 mm screen) were transported in 250 mL serum bottles containing 200 mL liquid (artificial saliva and ruminal liquor in a 2∶1), and incubated at 39℃. Total gas production by the original plant solid powder was the highest, monensin treatments the lowest, and ethanol extracts were intermediate. Although the treatments of both I. balsamina and monensin reduced methane production, it was lowest in the original plant solid powder treatments. Monensin treatments reduced carbon dioxide production while I. balsamina increased it. Furthermore, the treatments of I. balsamina preparations and monensin reduced ammonia nitrogen (NH₃-N), and as I. balsamina contents increased, ammonium nitrogen production decreased. The MCP of monensin treatments was the least, while those of original plant solid powder treatments (S1, S2, S3) were significantly higher than that of the control and monensin treatments. Monensin treatments reduced the contents of acetate and total volatile fatty acid but increased propionate. Treatments of I. balsamina increased the volatile fatty acids contents,and compared with that of the control, the volatile fatty acids contents of ethanol extracts and original plant solid powder were increased by 12.9% and 20.2%, respectively. Moreover, the treatments of monensin and I. balsamina reduced the ratio of acetate to propionate. In conclusion, I. balsamina could reduce methane emissions, promote the conversion of NH₃-N to MCP, improve the metabolic model of in vitro rumen fermentation. The solid powder of I. balsamina was the most effective preparation.