A yolk antibody for SARS coronavirus is prepared through injecting the antigen, which may be recombinant genetic protein S, M, or E,or the antigen epitope for said protein able to represent SARS coronavirus, or the synthetic polypeptide of said protein, etc, in health hen for primary immunizing, booster immunizing, collecting its egg, extracting yolk, and extracting the yolk antibody from it. It can also be prepared to become liquid preparation. It can be used to prevent SARS.