Abstract: The report made use of the electron microscopy technology to examine the sick Pagrosomus Major at Qingdao in 1995 expounded, a lot of sphereovirus part icles which were found in the cytonucleus and cytoplasm of tissues of hepar, gut, kidney and grill. Study result showed: the sphereovirus had an irregular inclusion body in cytonucleus and cytoplasm at all, whose diameter was between about 80- 100nm. The virus particles had a middle density nucleus w ith an envelope. In diseased cells, nuclear chromatin changed and formed virus inclusion body , and part of the nuclear envelope was dissolved and distributed a lot of ribosome.. s over the cytoplasm, part of the outer membrane and crest of mitochondrion were out of shape and dissolved.