The invention relates to the chemical heat treatment process engineering of metallic materials, in particular to an anti-nitridation coating for low alloy structural steel components with the formula at the weight ratio as follows: tin powder 1, lacquer solvent 1-1.5, and Cr2O3 powder 0.1-0.2, wherein the lacquer solvent is prepared from lacquer and amyl acetate in the volume ratio of 1:1; or, the formula at the volume ratio as follows: tin powder 1, lacquer solvent 4-6, and Cr2O3 powder 0.4-0.7. The anti-nitridation coating of the invention can prevent the non-nitriding surface of the low alloy structural steel components from appearing nitrided layers in nitriding heat treatment, which facilitates the process and the use of the components for the future, and the anti-nitridation coating is easy to remove after the component nitridation.