Abstract: In order to explore extraction method of allicin from Chinese garlic, ultrasonic assisted aqueous twophase system extraction method was used on extraction of allicin from Chinese garlic. Using fresh garlic as material, with the extraction yield of allicin as an experimental index, the effect of operating conditions such as PEG mass fraction, ammonium sulfate mass fraction, p H and time of ultrasonic processing were investigated.Three-factor three-level experiment based on response surface analysis method was applied to optimize the extraction conditions, the simulated regression equation of prediction model was established. Results showed that the significance order of PEG mass fraction, p H and time of ultrasonic processing was:p H >PEG 4000 mass fraction>ultrasonic time. The optimal extraction conditions for PEG 4000 mass fraction of 19.4%, p H3.0, ultrasonic processing time of 55 minutes. Under this condition, the prediction value of extraction yield of allicin was 88.91%, the experimental value was 88.89±0.0112%, which were almost consistent with the prediction value.