Abstract: In order to analyze the key sour taste components in leaf tobacco, the extract of cured tobacco was separated by gel permeation chromatography (GPC). According to the taste characteristic of each fraction, the sour taste characteristic components (STCCs) were obtained by categorization. A quantitative method based on ion chromatography was developed to determine five selected organic acids (lactic acid, levulinic acid, malic acid, fumaric acid and citric acid) in the STCCs. On the basis of quantitative data, the mixed solutions of the five organic acids were recombined, and the taste dilution analysis (TDA) of STCC solutions and the recombined solutions was conducted. The taste thresholds of the five organic acids in water were determined by three-alternative forced-choice (3-AFC) method, then their taste activity values (TAVs) were calculated by taking into account their contents in STCCs. The results showed that: 1) The maximum dilution multiple of STCC solutions was consistent with that of the recombined solutions in TDA experiment, it proved that the five acids were the main sources of sour taste in STCC solution. 2) According to their TAVs, the five acids in the order of their contribution to sour taste were malic acid > lactic acid > levulinic acid >citric acid >fumaric acid.