The acidified liquid of food waste had a high concentration of organic acids, providing an additional carbon source for the denitrification process in wastewater treatment, potentially alleviating the common problem of carbon source scarcity in urban sewage treatment plants in China. Based on fully mixed anaerobic fermentation reactors, the effects of different pH values, organic loading rates (OLR), hydraulic retention times (HRT) on the anaerobic acidification characteristics of food waste under continuous operation were investigated. By regulating the types of anaerobic acid production, different types of acidification liquids were obtained to evaluate their performance as additional carbon sources for wastewater denitrification. The results indicated that controlling the pH value at 6.0 and the OLR at 15.0g/(L·d) yielded the maximum production of TVFAs at 50.05g/L, with butyric acid fermentation being predominant. When the pH value was controlled at 5.0, acetate-type fermentation occurred, exhibiting the optimal denitrification rate of 7.62mg/(g·h), which was between that of glucose (5.39mg/(g·h)) and sodium acetate (9.47mg/(g·h)). At equivalent COD levels, the denitrification capability of the acidified liquid of food waste (0.21g/g) was 84% of that of sodium acetate. Therefore, food waste acidification liquid represented a sustainable, low-energy and cost-effective renewable carbon source with significant market and application potential.