objective:to study the effect and mechanism of sphingosine kinase inhibitor ski-Ⅱ on the apoptosis of human gastric cancer cell sgc7901. methods:sgc7901 cells were cultured and treated with ski-Ⅱ alone or in combination with cisplatin(ddp).the apoptosis of the tumor cells was analyzed by flow cytometry;the morphological changes were observed by electron microscopy;the expression of sphk1,nf-κb,bcl-2 and bax were detected by immunocytochemistry and western blot. pearson analysis was used to detect the correlations between sphk1 and nf-κb,nf-κb and bcl-2. results:after treated for 48 h,the apoptosis rates in sgc7901 treated with ski-Ⅱ 5,10 μmol/l,ddp 2.5 mg/l,ddp 2.5 mg/l+ski-Ⅱ 5 μmol/l and ddp 2.5 mg/l+ski-Ⅱ 10 μmol/l were (40.39±1.06)%,(45.58±0.75)%,(47.27±1.13)%,(53.64±1.11)% and (66.98±2.32)%,respectively,compared with the control group[(18.46±1.64)%],the differences were significant(p < 0.05). apoptotic bodies were found in sgc7901 cells by electron microscopy. the expression of bax was increased,but the expression of sphk1,nf-κb and bcl-2 was decreased. and the correlations between sphk1 and nf-κb,nf-κb and bcl-2 were positive. conclusion:ski-Ⅱ could induce the apoptosis of sgc7901 cells through down-regulating the expression of sphk1 and nf-κb,and increasing the ratio of bax/bcl-2.