Objective VP1 protein of foot-and-mouth disease virus(FMDV) is the most antigenic protein being responsible for eliciting neutralizing antibodies and conferring protective immunity.The successful expression of VP1 gene in Bac-to-Bac expression system should lay a foundation for research of FMDV Type O serology method.Methods\ We inserted VP1 gene of Foot-and-Mouth virus type O into pFastBacHIa vecter to get recombinant plasmid pFastBacHIa-VP1.The recombinant plasmid was transferred into DH10Bac containing a shuttle vector Bacmid and the VP1 gene was integrated into Bacmid by site-specific transposition.Subsequently, the recombinant shuttle vector Bacmid-VP1 was transfected with Sf9 cells.Results\ SDS-PAGE electrophoresis and Western blot analysis detected a band of about 26.4 kDa protein in the expression product of VP1 gene in insect cells.Conclusion\ The successful expression of VP1 gene in Bac-to-Bac expression system should lay a foundation for research of antigenicity and immunogenicity of VP1 protein as well as the surveillance of antibody.