The effects of high pressure processing(HPP) at 300~600 MPa for 15 min on organic acids and VC in blackberry(Rubus Hull.) juice were detected by using reversed-phase high performance liquid chromatograp method and 2,4-Dinitrophenylhydrazine colorimetry method respectively.Their synergistic antioxidant capacities were also evaluated.In blackberry juice,the dominant acid was L-malic acid,which constituted 87.98% of total acids.While α-ketoglutaric acid,acetic acid,citric acid,and butanedioic acid were detected in low amounts.After application of pressure,L-malic acid and butanedioic acid were significantly changed(P<0.05).However,no significant changes in other organic acids(P>0.05).L-malic acid in juice decreased by 12.2% after 300 MPa processing for 15 min,while increased by 8.53%,6.08% and 22.35% respectively at 400~600 MPa processing for 15min.Compared with the control juice,the contents of VC were well retained and ranged from 90.10% to 97.92% at 300~600 MPa.L-malic acid enhanced the scavenging activity of VC on DPPH· with its concentration increasing,which indicated that L-malic acid synergistically enhanced the antioxidant capacity of VC.