Objective To extend the survival time of diabetic rat in order to observe the formation and development of diabetic retinopathy(DR).Method 70 SD rats were divided randomly into control group(n = 20) and DR group(n = 50).Streptozotocin(STZ) in a dose of 60 mg/kg was injected into peritoneal cavity to induce diabetes mellitus.DR group rats were killed at 6~(th),9~(th) and 12~(th) month,respectively.Retina microvasculature was digested,stretched,PAS stained and used to examine the DR microvascular alteration.Result Diversified lesions occurred with the progressing of survival time.The most serious arteriolosclerosis occurred at 12~(th) month.Conclusion The prolongation of survival time of diabetic rats is beneficial for investigation of the progression of diabetic retinopathy.