Aim To explore the role of changes of intracellular pH in expression of apoptosis-related genes of cultured vascular smooth cells induced by neuropeptide Y. Methods The rat vascular smooth muscle cells were used for experiments at passage 4 to 6. The expression of bcl-2 and bax were quantitatively detected in cultured vascular smooth muscle cells and the intracellular pH were also quantitatively detected with the immunofluorescent quantitative skill through Laser scanning confocal microscope (ACAS570). Results It was found that at the action of NPY (10 -6 mmol/L), bcl-2 and bax were markedly expressed in cultured smooth muscle cells compared with control group. The fluorescent value of bcl-2 and bax were 1 349.67±108.28 and 1397.50±104.43, much higher than 921.72±80.31 and 1 060.44±107.54 in the control group respectively (P<0.01). Intracellular fluid pH in VSMC was decreased by NPY. Conclusion The expression of apoptosis-related genes induced by neuropeptide Y is mediated, in part, by intracellular acidosis in cultured vascular smooth muscle cells.