Abstract: In order to optimize the extraction process of active substances from high-quality forage grass Qianzhong Fagopyrum dibotrys in Guizhou Province, and to explore the antibacterial activity of the extracts, in this experiment, the aboveground and underground parts of Qianzhong Fagopyrum dibotrys were extracted by reflux method, ultrasonic method, boiling method and fresh sample juicing method. The antibacterial effect of each extract on Grape aureus, E. coli and Salmonella in vitro was detected by perforation method, and the extraction method was determined. The antibacterial effect of each extract on Staphylococcus aureus, Escherichia coli and Salmonella in vitro was detected by perforation method, and the extraction method was determined. High performance liquid chromatography（HPLC） was used to detect the content of effective substances in the extracts; the solution concentration, material-liquid ratio and extraction temperature were optimized, and the orthogonal test was set to determine the optimal extraction process. The minimum inhibitory concentration（MIC） and minimum bactericidal concentration（MBC） of Qianzhong Fagopyrum dibotrys extracts against three bacteria under optimal extraction conditions were detected by microbroth double dilution method. The results showed that the 70% ethanol ultrasonic extracts of the underground part of Qianzhong Fagopyrum dibotrys had inhibitory effect on all three kinds of bacteria, and had the best antibacterial effect on Staphylococcus aureus, with an inhibition circle diameter of 24.2 mm. The optimal extraction process was ethanol concentration of 50%, extraction temperature of 60 ℃, and material-liquid ratio of 1∶40. The MIC of the extracts against Staphylococcus aureus, Escherichia coli and Salmonella ranged from 31.25 to 62.5 mg/mL and the MBC ranged from 62.5 to 500 mg/mL, and its MIC and MBC against Staphylococcus aureus were 31.25 mg/mL and 62.5 mg/mL, respectively. The results indicated that alcohol extracts of the underground part of Qianzhong Fagopyrum dibotrys had inhibitory effect on Staphylococcus aureus, Escherichia coli and Salmonella, good inhibitory effect on Staphylococcus aureus, and had practical feasibility when used as a reducing anti-feed additive product.