Abstract: Protein from Jerusalem artichoke was extracted by ultrasonic auxiliary alkaline and some functional properties of the protein were analysed. The extraction process was optimized by orthogonal array design method. The results showed that the highest extraction vield of 71.2%±0.3% was achieved at p H of 13.5, solidto-liquid ratio 1∶40 (mg/m L) , ultrasonic duration 50 min and ultrasonic temperature of 60℃. The isoelectric point of the protein was around 4.0 and the emulsifying capacity could reach 80% at p H9.0. Meanwhile, the foaming ability was highest with the protein concentration of 4% and the solubility was highest at 70℃.