Abstract: [Objective]Interleukin-18(IL-18) is a proinflammatory cytokines that plays a key role of immune regulation through activating the Th 1 cell and NK cell secreting interferon-γ(IFN-γ). IL-18-binding proteins(IL-18BP) secreted in human and mouse can antagonise the activity of IL-18. The homologue gene of IL-18BP from fowlpox virus genome is predicted and identified of its expressed protein，which is helpful to use as an antagonist to IL-18 guiding disease. [Methods] The cIL-18BP gene was isolated from the genome of fowlpox vaccine virus by PCR through a pair of special primers and cloned into vectors pPICZαA，then expressed in yeast GS115. The biologic activity of recombinant proteins binding with cIL-18 was measured, inhibiting the activity of cIL-18 enhancing relative cells secreting IFN-γ was confirmed through ELISA. [Results] The cIL-18BP gene was cloned from fowlpox virus and acquired high performance expression in yeast systems induced with methanol identified by SDS-PAGE. Recombinant cIL-18BP purified can bind specifically with recombinant cIL-18 determined by ELISA test. cIL-18BP can antagonise the activity of cIL-18 with determining the IFN-γ concentration secreting in PBMCs and MSB1 cells stimulated by cIL-18 respectively. [Conclusion] The experiment indicates that recombinant cIL-18BP can inhibit the activity of cIL-18 stimulating related immune cells secreting IFN-γ. Deletion of the cIL-18BP from virus may improve the safety and immunogenicity of fowlpox virus vaccine.