Abstract: Using guava leaf as raw material,extraction of guava leaf polyphenol by ultrasound- assisted method was studied in this paper.The influence of various factors on the extraction efficiency of polyphenol was discussed.With quadratic response surface design,the optimal extracting conditions for ultrasound- assisted extraction were established: 51% alcohol( v / v),the 1∶ 30( g / m L) of material- solution ratio,60 ℃,60 W ultrasonic power for 47 min.Under these conditions,the content of polyphenol reached 143.38 mg / g.