The diameters、perimeters and areas of normal cell nucleus and cell nucleus infected with Penaeus monodon baculovirus(MBV) in hepatopancreas epithelial cells of Penaeus monodon were studied by micro-imaging analytical technique.The results show that the mean diameter is 3.47±0.30 μm,the mean perimeter is 13.03±1.36 μm and the mean area is 10.87±1.78 μm² in normal cell nucleus,while the mean diameter is 3.81±0.79 μm,the mean perimeter is 14.00±2.87 μm and the mean area is 13.52±5.37 μm² in the cell nucleus infected with MBV.There was significant difference between them(P<0.01).Three type occlusion bodies(OB) were measured.The biggest OB is type I and the smallest OB is type III.The most common OB is type I.