[Objectives]  Spodoptera exigua is a major agricultural insect pest that damages the growth of many vegetable crops. The peritrophic membrane (PM) is a semipermeable membrane secreted by insect midgut cells that plays an important role in digestion and protects insects from microbes and parasites. The aim of this study was to identify the protein constituents of the S. exigua peritrophic membrane, in order to increase understanding of the molecular interaction between the PM and pathogenic microorganisms. [Methods]  The PM of 5th instar S. exigua larvae were removed and treated with trifluoromethane-sulfonic acid (TFMS). The peritrophic membrane proteome of larvae was identified by liquid chromatography and mass spectrometry (LC-MS/MS), and the results subjected to bioinformatics analysis. BLAST software was used to compare protein homology online and to explore horizontal gene transfer. [Results]  A total of 199 peritrophic membrane proteins from Spodoptera exigua larvae were identified. These proteins could be enriched in 84 GO terms (P<0.05). KEGG enrichment results categorized the identified proteins into 73 metabolic pathways. The results of protein-protein interaction (PPI) analysis indicate that the identified proteins form multiple interaction networks and participate in various processes, such as energy metabolism, protein hydrolysis, hydrogen peroxide metabolism and immunity. The identified proteins included stress-related proteins which are involved in detoxification and metabolism. Such proteins can improve the resistance of insects to pesticides and harsh environmental conditions. [Conclusion]  A total of 199 peritrophic membrane proteins of S. exigua larvae were identified and analyzed. The results provide useful information on the potential biological function of the PM and facilitate the development of novel, effective, biological pesticides.