Objective To investigate the effect of silencing Huntingtinassociated protein 1（HAP1）on apoptosis of mouse pancractic islet beta cells line(NIT cells). Methods 1.The NIT cells were transfected with chemically synthesized siRNA targeting HAP1 for comprehensive evaluation of its silence efficacy. 2.The expression of the silencing HAP1 was detected by Annexin V and PI, and TdT-mediated dUTP-biotin nick end-labeling (TUNEL) to evaluate its efficacy on the apoptosis of NIT cells. 3. The expression of the silencing HAP1 was detected by Annexin V and PI to evaluate its efficacy on the streptozotocin (STZ)-induced apoptosis of NIT cells. Results The expression of silencing HAP1 in NIT cells was inhibited significantly by chemically synthesized siRNA targeting HAP1; The number of the apoptosis of NIT cells based on estimates of the difference between experimental and control group, it was markedly increased in the group transfected with chemically synthesized siRNA targeting HAP1 as compared with the control group (P<0.01); STZ-induced apoptosis of NIT cells was significantly increased (P<0.01), and the expression of silencing HAP1 was sufficient to promote STZ-induced apoptosis of NIT cells (P<0.01). Conclusion The expression of silencing HAP1 increases the apoptosis of mice pancreatic islet beta cells line NIT, and it enhances the capability of apoptosis-inducer, STZ and to quicken the apoptosis of NIT cells in s