Abstract: In order to study species and concentration of organic acids and in vitro antioxidant activity of raspberry-ferment and blueberry-ferment, high performance liquid chromatography was used and reducing power as well as scavenging activities on DPPH radical, superoxide radical, hydroxyl radical and ABTS+radical were investigated. The results of this study showed that the main organic acids of raspberry-ferment and blueberry-ferment all were tartaric acid, acetic acid and citric acid.Meanwhile, pyruvic acid, shikimic acid and fumaric acid were accumulated for metabolism and gallic acid was not detected in blueberry-ferment. The reducing power and scavenging activities on DPPH radical, superoxide radical, hydroxyl radical and ABTS+radical cation of raspberry-ferment and blueberry-ferment all exhibited a dose-dependent manner.In the experimental dose range, The raspberry-ferment and blueberry-ferment DPPH radical scavenging capacity of IC₅₀ were 2.00 mg V_C equivalent/m L and 8.70 mg V_Cequivalent/m L, the reducing power of IC₅₀ were 4.53 mg V_Cequivalent/m L and 7.62 mg V_C equivalent/m L, the superoxide radical scavenging capacity of IC₅₀ were 0.53 mg V_Cequivalent/m L and 2.05 mg V_Cequivalent/m L, the hydroxyl radical scavenging capacity of IC₅₀ were 8.92 mg V_Cequivalent/m L and 9.14 mg V_Cequivalent/m L, the ABTS+radical scavenging capacity of IC₅₀ were 3.59 mg V_Cequivalent/m L and 6.81 mg V_C equivalent/m L.The above results suggested that the type of organic acids in raspberry-ferment were higher than those in blueberry-ferment, raspberry-ferment and blueberry-ferment both had a good effect on scavenging free radicals, but scavenging free radical activities in raspberry-ferment were higher than those in blueberry-ferment overall.