Abstract: Objective 　To screen NS gene specific positive cell clones, and investigate the effect of human esophagus cancer Eca-109 cells proliferation in vit ro by NS gene specific RNA interference. Methods 　The NS-siRNA expression vector was transfected into human esophagus cancer Eca-109 cells using LIPOFECTAMINE^TM 2000 Reagent, and positive clones were examined by PCR af ter stable transfectans screening with Zeocin ; detected the cell proliferation by MTT assay and the levels of NS gene expression by RT-PCR. Results 　Compared with the two control groups, the silencer group cells were nearer differetiation, the proliferation inhibitory rate was higher than 80 %( P < 0. 01) ; the level of NS gene expression reduced. Conclusion 　The NS gene specific RNAi can significantly inhibit human esophagus cancer Eca-109 cells proliferation in vitro and reduce the level of NS gene expression.