Abstract: In order to identify new anti-mycobacterial natural products or new antibacterial sensitizers from medicinal plants, the anti-mycobacterial activity of crude extract of Forsythia suspensa (Thunb.) Vahl. (Fs for short) was performed. Boiled method and ultrasonic method were used to extract whole plant of Fs. Two kinds of extracts were subjected to antibacterial test in vitro by 96 microtiter plate dilution method. The ultrasonic extract of Fs was extracted by organic solvent (petroleum ether, dichloromethane, ethyl acetate and n-butanol). Finally, the antibacterial effect of dichloromethane extract of ultrasonic extract of Fs combined with antibiotics was explored by bactericidal curve method. The results showed that when the Fs extract was used alone, the saturated concentration of the Fs water extract had no antimicrobial activity, while the MIC value of the ultrasonic extract of Fs was 3 mg/mL. Further experiments proved that the alcoholic extract of Fs and its organic solvent extracts show different levels of synergistic antibacterial effects when used in combination with selected antibiotics. The dichloromethane extract of ultrasonic extract of Fs combined with antibiotics can effectively improve the antibacterial effect on mycobacteria and prolong the bacteriostatic time. There were antibacterial synergistic agents with antibiotics in Fs, which laid a certain foundation for the extraction of natural antibacterial products from medicinal plants.