Abstract:Natural ferment of Rosa roxburghii was manufactured at three proportions（mass ratio，1 ∶1，2 ∶1，4 ∶1）between fruits and rock candy.The content of Vitamin C （VC），total phenol，flavonoid，carotenoid and superoxide dismutase（SOD）activity were determined in natural ferment and in fruits after Rosa roxburghii natural fermentation.The superoxide anion radical （·O2－），hydroxyl radical（·OH）and 1，1-，two phenyl，-2-hydrazine group free radical（DPPH·）systems were used to analyze antioxidant activity in vitro.And the correlation between the antioxidant substances and antioxidant activity was compared.The result showed that VC，total phe nol，SOD activity，·OH clearance and·O2－clearance were highest in natural ferment at a proper proportion（1 ∶1）between fruits and rock candy，reached to 1 519.31mg/100mL，60.65mg/mL，8 571.43 U/mL，78.69%and 98.66%respectively，in which VC，total phenol and SOD activity were significantly to very significantly positively correlated to·OH clearance and·O2－clearance.In addition，the total phenol，flavonoid，carotenoid，·OH clearance and DPPH·clearance were at tiptop in fruits after Rosa roxburghii natural fermentation at another proportion （4 ∶1）between fruits and rock candy.The values were severally 32.05mg/100 g，13.55mg/g，37.58mg/g，62.42%and 95.33%.And the total phenol，flavonoid and carotenoid were significantly to very significantly positively correlated to·OH clearance and DPPH·clearance.Whether in natural ferment or in fruits after Rosa roxburghii natural fermentation，very significantly positive correlation was always observed between total phenol and·OH clearance.