Abstract： Objective To study the relationship between serum level of TNF-α and morphologic changes as well as related factors in 3 and 6 months of diabetic retinopathy rats. Methods This research successfully duplicated a model of insulin dependent diabetes mellitus in rats and carried out morphologic observation of retina of diabetic rat when the disease lasted for 3 and 6 months. The serum level of TNF-α by ELISA together with related factors, such as blood glucose (BG)by oxidase method、glucosylated hemoglobin (GHbAlc) 、serum insulin (Ins) and c-peptide (C-P) by RIA were studied. Results In same duration,the levels of TNF-α、BG、GHbAlC in model groups were significantly higher than therapy groups (P<0.01), the levels of Ins and C-P were significantly lower. Morphologic changes were clear. In different duration of model groups,the level of TNF-α in 6 moths groups was significantly higher than that of 3 months. Morphologic changes were clear in 6 months. There was no different in serum TNF-α、BG、GHbAlC、Ins、C-P between different duration of therapy groups. Conclusion The serum level of TNF-α was related with morphologic changes of retina、poor blood glucose、duration. The high level of TNF-α was a risk factor for the development of DR. It maybe an index to monitor the progression of DR.