Abstract: Objective To study the killing effect on liver cancers by mouse macrophages stimulated by Newcastle disease virus 7793 strain in vitro and the association of TRAIL. Methods The BALB/C mouse macrophages were harvested by using peritoneal lavage.And then the mouse macrophages were stimulate in vitro by NDV7793.The concentration of TNF-α and TRAIL was determined by ELISA after NDV stimulation.Then the macrophages of mice were coincubated and activated with Novikoff cells.The cytotoxic effect of macrophages on Novikoff cells was performed by Lactate Dehydrogenase(LDH) assay after NDV stimulation.Three experiment control groups were simultaneously set up as following:IFN-β positive control group,ultraviolet ray inactivated NDV(UV-NDV) control group as well as blank control group. Results Compared with three control groups in vitro,the macrophages stimulated with NDV 7793 had been activated,and the level of TNF-α and TRAIL in culture supernatant increased.The killing ability of macrophage to Novikoff cells after NDV stimulation had increased. Conclusion The NDV 7793 can activate the mouse macrophages in vitro.The killing effect on liver cancer cells of the mouse macrophages is enhanced by NDV stimulation.And it is possible that TRAIL and TNF-α involve in this may enhance the killing effect.