We have sequenced the polyhedrin gene from LsMNPV and the deduced amino acid sequence was compared with other polyhedrin or granulin amino acid sequences from 22 baculoviruses. Conservation of amino acid sequences was counted using a curve and a model polyhedrin (MPh) was given reasonably. Hydrophilicity of MPh and polyhedrins from some representative baculoviruses was studied by the PROSIS software. Prediction of secondary structure of MPh and 23 polyhedrins was stated in computer. Relationship among the predicted structure in special amino acid regions and the variability, the hydrophilicity was found. Evolution of 23 baculoviruses was discussed according to the maximum homologous analysis of amino acid sequences between two polyhedrin separately.