Abstract: Ultrasonic batch extraction of curcumin from Curcuma longa L. had been carried out with an ultrasound cleaning bath (0.25W·cm^-2, 50kHz, 338K), and it was investigated that the influence of particle size, ratio of solvent to solid and ethanol volume fraction on the concentration of the curcumin. According to the Fick law, the dynamic model of curcumin ultrasonic batch extraction was deduced by using the separation of variables method, and the modified model fits the experiment data well. Comparing to conventional extraction, the influence of ratio of solvent to solid decreased by 6.22%, but the effect of particle size and ethanol volume fraction increased by 29.9% and 8.18%, respectively. The possible causation of particle size, ratio of solvent to solid and ethanol volume fraction effects in the extraction was discussed, and the changes in these three factors caused by ultrasonic properties accordingly affect on the effect of the extraction. Therefore the modified model can provide the valuable theory basis for the technical design of curcumin extraction process.