The invention provides a homocysteine detecting kit and a using method thereof, relates to the field of biochemical detection, and aims to provide a homocysteine detecting kit which is high in stability, high in accuracy and high in precision and a using method of the homocysteine detecting kit. The homocysteine detecting kit comprises a reagent 1 and a reagent 2, wherein the reagent 1 comprises a capso buffer solution, lactic dehydrogenase (LDH), L-serine, reduced coenzyme Thio-NADH, tris((2-carboxyethyl)phosphine, mercaptoethanol, an alkylphenol polyoxyethylene series, EDTA, polyethylene glycol 300, ascorbic acid oxidase, a composite stabilizer, and a proclin series preservative; and the reagent 2 comprises a capso buffer solution, cystathionine-beta-synthase, methionine synthase, cystathionine-beta-lyase, methionine-gamma lyase, a surfactant and sodium dodecylbenzene sulfonate. By the various added mixed enzymes and methionine-gamma lyases, the accuracy of the kit on detection of homocysteine can be improved.