The purification efficiency of (+)-dihydromyricetin, a bioactive plant flavonoid, was remarkably improved through ultrasound-based fractional precipitation. The precipitation time (up to 30 min) taken to obtain (+)-dihydromyricetin with high purity (87.01-91.66%) and yield (90.63-92.00%) through the ultrasonic fractional precipitation (ultrasonic power: 80-250W) was shortened by 40-fold as compared to the conventional method (up to 1200 min). In addition, the precipitation rate constant was increased by 12- to 18-fold, but the activation energy was decreased to between -5,787 J/mol and -6,526 J/mol, and thereby the precipitation rate was improved. Furthermore, the size of the precipitate was reduced by 5.1- to 5.5-fold, while the diffusion coefficient was increased by 6.4- to 6.9-fold.