Background: Meta-analysis was used to evaluate the efficacy and safety of aspirin combined with letrozole in the treatment of polycystic ovary syndrome (PCOS).Methods: Through comprehensive searches of the China Knowledge Network (CNKI), the VIP database (VIP), the Wanfang database, the China Biomedical Database (CBM), PubMed, EMBASE, and the Cochrane Library, the clinical randomized controlled trials (RCTs) published on aspirin combined with letrozole in the treatment of PCOS were collected. According to the inclusion and exclusion criteria, the included studies were screened and quality evaluated, and RevMan 5.3 software was used for meta-analysis.Results: A total of 10 RCTs and 948 patients with PCOS were included. Meta-analysis results showed that compared with letrozole monotherapy, aspirin combined with letrozole could significantly increase the thickness of the endometrium [MD=1.