Abstract: A novel preparation method for the anti-gout drug Lesinurad, and a key intermediate thereof. The method comprises the following reaction steps: 1) the compound of formula II undergoing a substitution reaction with R3—SH in the presence of a first solvent and a first alkali to generate a mixture containing the compound of formula III and the compound of formula IV; 2) adding a second alkali and R3X to the resulting mixture for a reaction to obtain the compound of formula III, wherein: R represents a cyclopropane group, a halogen, a triflate group, a mesylate group or a tosylate group, preferably a cyclopropane group; R3 represents —COCH3, a benzyl group or —CH2R4, wherein R4 represents a methyl acetate group, an ethyl acetate group, —C(O)OC2H5, —C(O)OCH3, —CN, —CH2OH or a phenyl group substituted with one or more of a C1-C6 alkyl group and a halogen; X represents a halogen.