Objective To construct small interfering RNA（siRNA）expression vector and to investigate its inhibitory effect on vascular endothelial growth factor-C（VEGF-C） expression in human breast cancer cell line MCF-7 Methods A pair of hairpin-like oligonucleotide sequences specific for VEGF-C gene were designed and synthesized.The annealed oligonucleotide fragments were subcloned into plasmid pRNAT-U6.1/Neo to construct VEGF-C siRNA expressing vector.Then VEGF-C siRNA expression vectors were confirmed by PCR and sequencing.Transfection of VEGF-C siRNA expressing vector into MCF-7 cells was performed using liposome transfection reagents.VEGF-C mRNA and protein expression were examined by RT-PCR and immunocytochemistry respectively. Results PCR and DNA sequencing showed that siRNA expression vector targeting VEGF-C was successfully constructed.VEGF-C expression in the cells transfected by VEGF-C siRNA expression vectors was inhibited significantly at both mRNA and protein levels.VEGF-C mRNA and protein expression were decreased 61.8% and 78.3% compared with control plasmid respectively（EM>P/EM>0.05）.Conclusion VEGF-C siRNA expression vector can effectively inhibit the expression of VE