Abstract: Objective 　To const ruct several eukaryotic plasmid expressing shRNA of gene bi21 which de2 rived f rom the eukaryotic plasmid pmU6 and study the effect on proliferation of CNE22Z, CNE21, HO8910, HO8910 PM. Methods 　Oligonucleotides of bi21 were synthesized and inserted into the eukary2 otic expression vector pmU6 in definite direction. Cells were t ransfected with recombinant plasmids, MTT assay was applied to evaluate proliferation of cells affected by LipofectmineTM 2000 and the plas2 mids. Results 　Compared with unt reated group, t ransfected with recombinant plasmids group may inhibit proliferation of CNE22Z, CNE21, HO8910PM markedly, but can not inhibit proliferation of HO8910. Conclusion 　The shRNA expressed by the recombinant plasmid can sufficiently induced RNAi and inbibit cell proliferateion in some tumor cells, and these observations may open a path toward the use of plasmid2 mediated RNAi as a new tool for gene therapy research in human cancer.