Updated project metadata. Polycystic ovary syndrome (PCOS) is a common disorder encompassing reproductive, metabolic, and endocrine abnormalities, affecting 5 to 10% of women of reproductive age.To reveal the differences in proteomic profiles of follicular fluid between patients with and without PCOS and explore possible mechanisms underlying PCOS.Follicular fluid samples were collected from 9 infertile patients with PCOS and 9 infertile patients without PCOS. Quantitative proteomics analysis based on mass spectrometry was used to measure the protein levels and understand the protein networks. The tandem mass tag (TMT) based proteomics technology and bioinformatics analysis were used to determine the differentially expressed proteins(DEPs). : In this study, we have identified a total of 1216 proteins,these included 70 DEPs, in which 32 proteins were upregulated, and 38 proteins were downregulated. The bioinformatics analyses revealed multiple biological functions associated with these DEPs, some DEPs were enriched in the immune and metabolic-related biological processes in PCOS patients.