The invention discloses a liquid stable enzymic method homocysteine kit. The liquid stable enzymic method homocysteine kit is characterized by comprising (1) a stable substrate system and (2) stable S-adenosyl-L-homocysteine hydrolase, wherein the stable substrate system comprises an NADH circulatory system and an S-adenosyl methionine polyanion system, and the stable S-adenosyl-L-homocysteine hydrolase improves the overall stability of the kit. By the adoption of the liquid stable enzymic method homocysteine kit, a stable system of S-adenosyl methionine and reduced coenzyme I is provided, the patented technology of enzyme is introduced so that the overall stability of the kit can be improved, and therefore the demand of clinical examination for the liquid stable enzymic method homocysteine kit is met; in addition, the defect that in the prior art, the clinical application of a kit is limited due to the fact that the stability of the substrate S-adenosyl methionine (SAM) is poor and the thermal stability of an adopted coupling enzyme is poor is overcome.