The invention discloses an immunopotentiator and a vaccine preparation for emergency vaccination of Newcastle disease. The active ingredient of the immunopotentiator is composed of sword bean hemagglutinin, panaxoside and astragalus polysaccharide; the vaccine preparation for emergency vaccination of Newcastle disease is composed of the immunopotentiator and Newcastle disease inactivated vaccine according to a volume ratio of 1: (5-25). After being emergently inoculated to chicken, the vaccine preparation disclosed by the invention can be used for effectively controlling the development of epidemic situation and replacing emergently inoculated virulent or attenuated vaccine, the attenuated vaccine not only brings poison and has the possibility of strong virulence return; on the other hand, the vaccine preparation can be used for compensating the defects of slow generation of antibody of the inactivated vaccine to unfavorably control the epidemic situation; meanwhile, the active ingredient of the immunopotentiator is composed of sword bean hemagglutinin, panaxoside and astragalus polysaccharide, and these extracts are active components extracted from plants, thereby meeting the requirements of environmental protection, moreover, the method is simple to operate, capable of quickly generating protective antibody, safe and effective, thereby having promotion significance.