Background. The relationship between onset age of diabetes and diabetic retinopathy (DR) is controversy and not concluded. Therefore, this hospital-based case-control study aimed to investigate the influence of diabetes onset age on the development of DR in patients with type 2 diabetes (T2D), independent of diabetic duration and HbA1c levels. Methods. A sample of 780 T2D patients with diabetic duration of 10-20 years and glycated hemoglobin (HbA1c) >= 7% were enrolled in the study. 338 T2D patients with onset age <45 years were further selected as cases Thearly onset) and 79 with onset age > 55 years were chosen as controls (elderly onset). International Clinical Diabetic Retinopathy Disease Severity Scale was applied to estimate the severity of DR. Results. The prevalence of DR and proliferative diabetic retinopathy (PDR) was notably increased in the early onset group. When stratified by duration of diabetes, the impact of younger age on the risk of DR turned to be greatest in patients with diabetic duration >= 15 years (OR. 5.202, 95% CI 2.625-10.310). In groups stratified by HbA1c, the risk of DR was highest in patients with younger onset age and HbA1c >= 9% (OR. 3.889, 95% CI 1.852-8.167). Compared with the elderly onset group, the risk of DR (OR. 1.776, 95% CI. 1.326-2.380, p < 0.001) and PDR (OR = 1.605, 95% CI = 1.106-2.329, p = 0.013) in younger diagnosed patients was increased after multivariable adjustment. Conclusions. Age of onset was an independent risk factor for developing DR and PDR. This suggests that it is urgent to closely monitor and treat the metabolic disorders in younger T2D patients to delay the occurrence and progression of DR.