OBJECTIVE To construct a eukaryotic expression vector for RNA interference of the human cyclinD1 gene, and to detect its interference effect in human ovarian cancer cells (HO-8910).METHODS Four target gene segments were synthesized and cloned into the pSUPER vector respectively to construct four recombinant eukaryotic expression vectors, pSUPER-C1～4. The four recombinant vectors were identified by enzyme digestion analysis and DNA sequencing. Then HO-8910 cells were transfected with the pSUPER-C1～4 vectors and subjected to G418 selection. In G418-resistant cells, the interference effect was detected by RT-PCR.RESULTS Enzyme digestion analysis and DNA sequencing showed that the target segments were cloned into the pSUPER vector. The four recombinant vectors inhibited transcription of the cyclinD1 gene. The pSUPER-C2 vector had a better interference effect.CONCLUSION The sequence-specific siRNA effectively interfered with expression of the cyclinD1 gene that was selected. The transcription and expression of the cyclinD1 gene were inhibited effectively by the constructed RNAi eukaryotic expression vectors in the ovarian cancer cells. These results indicate that it is possible to search for a new tumor gene therapy method.