Abstract: Objective To study the autoimmunity of pancreas and self-repair of beta cells by establishing the low streptozotocin (STZ) dose- induced rat beta cell damage model. Methods Three days after SD rats were injected with STZ (40 mg/kg), their blood glucose, fasting blood glucose and fasting C-peptide levels were measured. Their pancreatic tissue samples were stained with H&E, insulin and CD8α. Their oral glucose tolerance was tested on day 54 and their blood glucose, fasting blood glucose, C-peptide levels and CD8α staining were measured on day 56. Results The blood glucose level was significantly higher in experimental group and blank control group than in fasting blood glucose group on day 3 after STZ treatment at the dose of 40mg/kg (33.00±2.31 mmol/L and 5.72±0.63 mmol/L vs 4.03±0.48 mmol/L). No significant change in blood glucose level was found in blank control group (3.50±0.41 mmol/L). The C-peptide level was higher in blank control group than in experimental group (0.29±0.03 ng/ml vs 0.23±0.03 ng/ml). Insulin immunohistochemistry showed beta cell damage and CD8αimmunohistochemistry showed positive expression of beta cells around the pancreas. The blood glucose level and CD8αexpression level were identical on day 3 after STZ treatment. However, the C-peptide level was higher in STZ treatment group than in blank control group with impaired glucose tolerance. Conclusion The secretion function of beta cells decreases and the aggregated CD8α-positive cells further damage the beta cells after the beta cells are damaged by low STZ doses.