Disclose a kind of antigen comprising recombinant respiratory syncytical precursor virus (RSV) F protein, wherein, recombination RSV F proteins include the antigenic re-gions that both ends connect with the regions HRN and the regions HRC, which includes one or more antigenic sites selected from site site II and the formed groups of site IV. The nucleic acid molecules for encoding the antigen are also disclosed, and the vaccine composition of the immune response for causing to fight RSV comprising the antigen.