Abstract: Hemorrhage of Gobiocypris rarus was induced by artificial infection of Grass carp hemor rhagic virus (GCHV). The ultra-thin sections of the tissues of the control and diseased fish were studied under electron microscope. No virions were discovered in the tissues of the control. The discovery of the aggregated GCHV particles in the endothelial cell cytoplasm of gill blood vessel indicated that the gill is one of the main organs infected by GCHV and this organ may take an important part in the spread and infection of GCHV. The aggregates of GCHV particles present in the cytoplasm of intestine and kidney cells suggested that the intestine and kidney are the other main organs of GCHV infection. In the spleen of the diseased fish, single virions were discovered in the cytoplasm of the cells with low electron density, and virion aggregates were rarely observed. These virions may come from the phagocytosis of phagocyte. We hold the view that the two kinds of viral particles, 40nm and 70nm in diameter respectively, represent different developmental stages of the GCHV.