Abstract: Objective 　To study the effect of newcastle disease virus to the immune response of tumor cells in vitro. Methods 　Newcastle disease virus lasota is studied in vit ro in four carcinoma cells including MCF-7 、Hela 、A549 and Hep G2, we also pret reated mice tumor cell with NDV L, then vaccine virus immunization on mice Balb/C to observe the influence. Results 　The apparent suppressive effect of NDV on the growth of these four tumor cells was found without does dependence. Pret reated with NDV, the tumor cells can promote the celluar immunity of mice in virto. Conclusion 　NDV can selective kill tumor cells in vit ro, NDV pret reated tumor vaccine can decrease the growth of the tumor cell, and have apparent immunostimulatory ability.