Abstract: Objective To elaborate the phasic change of β-cell apoptosis in single high streptozotocin (STZ) dose-induced type 1 diabetic model of SD rats. Methods A single high STZ dose (65 mg/kg) was injected into the abdominal cavity of SD rats and their blood glucose and insulin levels were measured. The rats were then sacrificed at the indicated time points and their pancreatic tissue was stained with H&E, immunofluorescence, and TUNEL, respectively. Results The rats showed the high-low-high blood glucose level accompanying the low-high-low insulin level and corresponding pathological changes after they were injected with STZ. The β-cell apoptosis (measured with TUNEL staining) increased dramatically 6 hours after STZ injection and sharply reduced 48 hours after STZ injection. The Β-cell apoptosis was hardly detected. Conclusion The β-cell apoptosis reaches its peak with corresponding changes in blood glucose and insulin levels and in pathological structure of islet 6 hours after a type 1 diabetic model of SD rats is induced with a single high STZ dose.