Purpose To investigate the association between metabolic syndrome (MetS) and diabetic retinopathy (DR), as well as the association between MetS and retinal vessel caliber, among Chinese patients with type 2 diabetes mellitus in north-eastern China. Study design Cross-sectional study. Patients and methods The patients were recruited from a community-based study, the Fushun Diabetic Retinopathy Cohort Study (FS-DIRECT). The presence of DR was determined using a modified version of the Early Treatment Diabetic Retinopathy Study (ETDRS) scale. The central retinal arteriolar equivalent (CRAE) and the central retinal venular equivalent (CRVE) were identified by use of Integrative Vessel Analysis software. The presence of MetS was defined according to the Joint Interim Statement proposed in 2009. Results The prevalence of DR was significantly higher among female patients with MetS than among those without it (47.2% vs 30.9%, P = 0.002), and it increased as the number of MetS components increased (P = 0.003). Furthermore, the presence of MetS (odds ratio 2.43, 95% CI 1.39-4.26) as well as higher numbers of MetS components were significantly associated with DR in female patients, after adjustment for potential risk factors. Patients with MetS (multivariate beta coefficient, 95% CI - 6.9, - 10.0, to - 3.8) or a higher number of Mets components tended to have significantly smaller CRAE. Conclusion In this study cohort, female patients with MetS had a higher prevalence of DR. Patients tended to have thinner central retinal arterioles as the number of MetS components increased.