Abstract: Objective To investigate the effect of Docosahexaenoic acid(DHA) combined with NS-398 on inhibition of cholangiocarcinoma QBC939 cell lines and its mechanism. Methods The cultured cholangiocarcinoma QBC939 cell line was exposed to 0,15,30,45,60 and 75 μg/ml DHA with 0,25,50,100,150 and 200 μmol/L NS-398,respectively.The absorbance of the QBC939 cells was measured by CCK8 and its growth inhibition ratio was calculated.Flow cytometry and transwell migration assays were applied to detect cell apoptosis and invasion,respectively. Results Exposure to DHA combined with NS-398 could significantly suppress the growth of QBC939 cells(P<0.05).When the concentration of DHA was 45 μg/ml and NS-398 was 100 μmol/L,the relative growth inhibition rate of QBC939 cells was 90%.If two drugs concentrations were increased,the result showed no statistically significant differences.DHA combined with NS-398 could promote QBC939 cells apoptosis at the early stage.When the concentration of DHA was 15 μg/ml and NS-398 was 50 μmol/L,it had no obvious inhibitory effect on QBC939 cell growth,but could obviously inhibit cell invasion,and significant difference was observed between the experimental and control groups(P<0.01). Conclusion DHA combined with NS-398 could promote apoptosis and inhibit growth and invasion of cholangiocarcinoma cells QBC939 in vitro.