The invention discloses a method for predicting the water-phase reaction rate constant of organic matter and a sulfuric acid free radical in a water phase through quantitative structure activity relationship. Based on a compound structure, a molecular descriptor with a structural feature is calculated, and by the adoption of a multiple linear regression method, a QSAR model of an organic compound kso4- is constructed. Establishment of the model strictly confirms to the constructing and using guideline of the QSAR model from organization for economic cooperation and development, the constructed model has a definite application field, contains 197 kinds of organic compounds of different structures, and contains compounds containing carbon-carbon double bonds, carbon-carbon triple bonds, a hydroxyl group, phenolic hydroxyl, a carbonyl group, an aldehyde group, a carboxy group, an ester group, an amide group, nitro, an amino group, a cyano-group, an ether bond, a disulfide bond, fluorine, chlorine, bromine, iodine, arsenium and other radical groups. The mode has good fitting capacity, robustness and predicting capacity, can rapidly and accurately predict the kso4- value of the organic compound, and reference is provided for application of an advanced oxidation process based on a sulfuric acid free radical.