The invention provides an aquatic nervous necrosis virus (NNV) vaccine and a method for preparing the vaccine. The method comprises Following steps: (a) culturing nervous necrosis viruses (NNV) by using a cell line to obtain a supernatant containing said nervous necrosis viruses (NNV), and (b) treating said supernatant with an inactivating agent to form an aquatic nervous necrosis virus (NNV) vaccine. Particularly suited inactivating agents are formalin and binary ethyleneimine (BEI). The aquatic nervous necrosis virus (NNV) vaccine can be further encapsulated by a nanoencapsulating process to form a nanoencapsulated aquatic nervous necrosis virus (NNV) vaccine.
