Abstract: The antimicrobial activitiy and scavenging DPPH· capability of extracts of seventeen Ampelopsis grossedentata samples with different content of dihydromyricetin( DMY) were studied. The extracts were prepared from leaves of A.grossedentata under ultrasonic wave- assisted ethanol extraction,the inhibition zone method was used to study the antibacterial activity of extracts,and the DPPH· radical scavenging effect of extracts was investigated using UV spectrophotometer method. In the meantime,antimicrobial activitiy and scavenging DPPH·capability of the contented DMY in extracts and the same concentration of standard DMY were determined to make comparisons. Results showed that all of these extracts had antimicrobial activitiy and scavenging DPPH·capability,and the activities were enhanced with the increasing of DMY content in the extracts. The antimicrobial activitiy and scavenging DPPH· capability of extracts were significantly stronger than the same concentration of DMY. Under the concentration of 10 mg / m L,some of the extracts expressed greater antibacterial activity than the same concentration of DMY,and for DPPH· scavenging capability,DMY has stronger than all extracts,extracts( No.10~17) have better than VCand extracts( No.2~17) have better than BHT.