This application relates to the technical field of diffraction grating protection, and specifically discloses a protection method for diffraction gratings, including S1, melting the paraffin into a liquid state; S2, dripping the melted paraffin on the surface of the diffraction grating; S3, bonding the protective glass on the On paraffin; S4, after the paraffin is solidified, the diffraction grating and protective glass are stored and transported as a whole; S5, when needed, put the diffraction grating and protective glass into an organic solvent capable of dissolving paraffin for rinsing, and after the paraffin is dissolved, take out the diffraction grating. raster. The protection method of the diffraction grating provided by the present invention has simple process, readily available materials, low toxicity, and low cost, and can effectively protect the surface of the grating from damage during the cutting process, thereby realizing efficient and high-quality manufacture of the diffraction grating.