Abstract: To investigate the inhibitory effects of RNAi（RNA interference） expression vector on the expression of avUCP gene. Four siRNA expression vectors (A, B, C and D) were constructed to be aimed directly at avUCP gene. The recombinants were transfected into myofibroblast with liposomes. Expression of avUCP was detected with fluorescence quantitative PCR（FQ-PCR）and flow cytometry. Four kinds of expression vectors could reduce the expression of avUCP mRNA and protein all in myofibroblast. The expression of avUCP mRNA reduced to 14.6% of control group, and the protein inhibition ratio reached 93.7%. The RNAi expression vector can effectively inhibit the expression of avUCP gene.