The invention discloses a recombination yeast engineering bacteria expressing reticuloendotheliosis virus Gp90 protein, its construction method and application. The recombination yeast engineering bacterial strain is preserved in CGMCC with the preservation number CGMCC No. 5046. With large scale induction of the engineering bacterial strain, the expression of Gp90 protein is 373 mg/L. The SDS-PAGE and Western blot detections prove that expressed recombination protein has biological activity and antigenicity of reticuloendotheliosis virus natural protein. By preparing an antigen vaccine from the recombination protein to immunize SPF chickens, the results show that: the recombination antigen vaccine can effectively induce the organism to generate specific humoral immune response to preventthe SPF chickens from attack of anti-REV, and can effectively prevent the propagation of the virus in body.