As silk is made up of proteins, their structures are easy to be changed by high temperature, high humidity, pollutants and other factors. In order to scientifically evaluate the influence of pollutant gases on silk fabrics structures, artificial simulated experiments were conducted to prepare common pollutant gas environments in museums, including nitrogen dioxide, sulfur dioxide, acetic acid and ammonia. The effects of the four kinds of pollutant gases on protein peptides, secondary structures and other aspects were investigated using Fourier transform infrared spectroscopy (FTIR). The experimental results showed that for silk fabrics aging with nitrogen dioxide for 30 h, there arose the peak of the methyl symmetric deformation vibration, near 1 382 cm-1, which did not appear on the samples aging with other gases for 50 days. It was shown that nitrogen dioxide had the most serious damage to silk fabrics. After aging with all pollutant gases, the absorption peaks of -Gly-Ala- and -Gly-Gly-peptide chains (primary structure) at 975 and 999 cm-1 were all reduced in varying degrees, but the effect of the alkaline gas ammonia on the peptide chains was more obvious than that of other acidic gases. The deconvolution of the amide Ⅲ band (1 330～1 200 cm-1) and Gaussian fitting results showed that the samples aging with ammonia for 50 days had only slight changes in the amorphous region with slight content changes of α-helix, random coil and β-sheet, and the secondary structures of silk protein did not change much. In comparison with ammonia, acid gases had a significant influence on the secondary structures of silk protein. The relative content of β-sheet was greatly reduced with that of random coils increasing significantly, and the crystalline region was damaged seriously. Among the four gases, nitrogen dioxide has the most significant effect on secondary structures of silk fabrics. The relative content of β-sheets decreased from 30.36% to 18.12% after 30 hours’ aging, which reduced about 40%. The nitrogen dioxide had the most serious damage to the strength of silk fabrics. With the declining of the β-sheet, the mechanical strength of the material decreased. The ratios of infrared absorption peaks at different wavenumbers A1 700/1 640 and A1 620/1 514 were used to judge the aging modes. Oxidation reaction occurred mainly to the samples aging with nitrogen dioxide, sulfur dioxide, and ammonia. Both oxidation and hydrolysis reaction happened to the samples aging with acetic acid. With the increase of aging time, the ratio of A1 620/1 514 of the samples aged with nitrogen dioxide increased most among the four gases and the oxidation was the most severe. It was inferred that it was related to the strong oxidizing property of nitrogen dioxide, also associated with the significant methyl symmetry vibration occurring of the silk fabric aging with nitrogen dioxide. It is suggested that the concentration of nitrogen dioxide gas should be strictly monitored and controlled in museums. This study provides a scientific basis for formulating a reasonable storage environment for silk cultural relics, and is of great significance to the protection of silk cultural relics.