The invention discloses an aviadenovirus Hexon and infectious bursal disease virus VP2 fusion antigen and subunit vaccine, and a preparation method and application of the aviadenovirus Hexon and chicken infectious bursal disease virus VP2 fusion antigen and subunit vaccine. The aviadenovirus Hexon and chicken infectious bursal disease virus VP2 fusion antigen comprises an aviadenovirus Hexon protein and an chicken infectious bursal disease virus VP2 protein. The fusion antigen has the following amino acid sequence: (1) a protein formed by an amino acid sequence as shown in SEQ ID No.1; or (2) an amino acid sequence of a functional protein with the same code and homology being 95 percent to 100 percent as the protein amino acid sequence limited by the sequence SEQ ID No.1. A protective antigen of the subunit vaccine prepared through the invention is the fusion antigen, and the fusion antigen is prepared by adopting a gene engineering fermentation method, and has the advantages of low cost, high antigen purity, good immunogenicity and high safety.