Objective：The current study aims to investigate the effect of argininosuccinate synthetase 1(ASS1)on cell proliferation and apoptosis of pancreatic islet β cells. Methods：Small interference RNA was used to knockdown ASS1，and lentiviral vector to overexpress ASS1 in pancreatic islet β cells. The 5-ethynyl-2′-deoxyuridine(EdU)and CCK-8 methods were used to detect proliferation ability，and Annexin V-PI flow cytometry and terminal dUTP nick-end labeling(TUNEL)were used to detect apoptosis. Western blot was used to examine protein expression of B -cell leukaemia -2(Bcl -2)，Bcl -2 associated X protein(Bax)，Caspase -3， cleaved Caspase-3，apoptosis inducing factor(AIF)，nuclear proliferation antigen Ki67 and mammalian rapamycin target protein (mTOR). RT-qPCR was applied to detect mRNA expression of AIF，Ki67 and mTOR. Results：①Proliferation activity of pancreatic β cells detected by EdU and CCK-8 was lower when ASS1 was knockdown，and apoptosis of islet β cells examined by TUNEL method and flow cytometry was higher than that in the control group. Meanwhile，the increased AIF expression and the decreased ratio of Bax/ Bcl-2 and the activity of Caspase-3 were observed. ②After overexpression of ASS1, the number of TUNEL positive cells and the apoptosis rate detected by AV/PI decreased compared to the control group, accompanied by expression levels of Ki67 and mTOR increased in pancreatic islets β cells. But there was no significant change in the positive rate of EdU and proliferative activity of cells by CCK -8 detected. Conclusion：Overexpressing ASS1 in pancreatic islet β cells may activate mTOR signaling pathway to promote cell proliferation. Pancreatic islet β cells with decreased ASS1 expression may initiate apoptosis through AIF pathway. In summary， ASS1 may play a role in proliferation and apoptosis of pancreatic islet β-cells.