The invention provides a method for inhibiting peroxidase activity by using fluorescent graphene quantum dots. The method comprises the following steps: (1) adding a carbon source into a certain amount of water to prepare a mixed solution, heating the solution until the moisture is completely evaporated, transferring the solution into a high pressure reactor, heating and reacting for a period of time, dissolving the product in water, regulating the pH value of the system to be neutral by using alkali liquor, purifying the product, and drying, thereby obtaining solid graphene quantum dots; and (2) dispersing the quantum dots obtained in the step (1) in secondary distilled water, taking a proper amount of quantum dot solution and enzyme solution, adding the solution into a buffer solution, adding a color developing agent and H2O2 after a period of time, uniformly shaking the mixed solution, rapidly adding the solution into a cuvette, measuring the light absorption value of the maximum absorption wavelength of the product on an ultraviolet-visible spectrophotometer, and performing blank sample control, thereby determining the relative enzyme activity. The graphene quantum dots are prepared by adopting low-price and readily available raw materials, and the method is green and environment-friendly. The structure of the enzyme can be changed by virtue of the interaction between the graphene quantum dots and zymoprotein, and regulation of the enzyme activity is realized.