OBJECTIVE： To optimize the ultrasonic extraction technology of total triterpenoids from the leaves of Perilla frutescens （TPL） and investigate its antibacterial activities against 10 kinds of common pathogens. METHODS： Using the extraction amount of triterpenoids as response value， the ultrasonic extraction technology of TPL was optimized by response surface methodology on the basis of single factor test with solid-to-liquid ratio， ethanol volume fraction， ultrasonic time and temperature as factors. The MIC and MBC of TPL on 10 kinds of common pathogens were detected by double broth dilution method， so as to investigate antibacterial activities. RESULTS： The optimal ultrasonic extraction technology of TPL included solid-to-liquid ratio of 1 ∶ 30 [m（g）/V（mL）]， ethanol volume fraction of 85 ％， ultrasonic time of 65 min and ultrasonic temperature of 75 ℃. Under these conditions， the amount of triterpenoids was 37.90 mg/g， relative error of which to predicted value （38.40 mg/g） was 1.30％. Measured value agreed well with predicted value. Results of antibacterial activities study showed that MIC were in the range of 0.48-15.50 mg/mL，and MBC≥0.97 mg/mL. TPL showed significant antibacterial activities， especially to Escherichia coli， Staphylococcus aureus and Pseudomonas aeruginosa. CONCLUSIONS： Optimized ultrasonic extraction technology of TPL is stable and feasible.  TPL extracted has strong broad-spectrum antibacterial effect and shows similar antibacterial effecton E.coli， S. anreus and P. aeruginosa.