The present invention relates to the field of animal virology, and provides a recombinant chicken-origin H9N2 avian influenza virus vaccine strain and a method for isolation, identification and purification of the strain. The invention further relates to a research of biological characteristics of the strain, especially to a research of characteristics of the strain adopted as the vaccine strain,and an evaluation of immune effects of the strain on SPF chickens. The preservation number of the strain is CCTCCNO:V201030. According to the present invention, the antigen variation conditions of the virus strain and other isolated virus strains are represented from the molecular level; after the virus strain is prepared into the vaccine, the prepared vaccine is adopted to immunize the 4 week old SPF chickens, with the protection effect analysis of the homologous H9 influenza wild virus strain and the heterologous H9 influenza wild virus strain, the results show that the influenza virus strain can be adopted as the spare vaccine strain of H9 subtype avian influenza. With the present invention, the spare vaccine strain is provided for prevention of the avian influenza outbreak by using the vaccine, the molecular biology technology program is provided for screen of the avian influenza virus vaccine strain, the molecular biology background is provided for study of the mechanism of animal infection by the avian influenza, and the important public health significance is provided.