The invention belongs to the technical field of preservation and particularly relates to a preservative based on gamma-aminobutyric acid combined with lactobacillus plantarum and application thereof in agaricus bisporus preservation. The preservative is lactobacillus plantarum clean water suspension wherein aminobutyric acid is dissolved, cell amount of the lactobacillus plantarum in the suspension is 10<6> to 10<7>cfu/mL, and concentration of the gamma-aminobutyric acid is 100 to 200mug/mL. The preservative disclosed by the invention can effectively inhibit brown strain of sporocarp, can keep hardness of sporocarp and prolongs a storage period of agaricus bisporus. The preservative disclosed by the invention has the advantages of safety, no toxicity and an excellent preservation effect, not only can avoid potential hazards brought by using chemical preservative to human and environment, but also can enhance a nutritional health-care effect of the agaricus bisporus. A preparation method of the preservative disclosed by the invention is simple, is simple to operate and convenient to use, can better conform to current preservative designing and developing directions and has better practical value and popularization and application prospect.