Abstract: The objectives of this study were to analyze the molecular characteristics and structure of major capsid protein(mcp) from Chinese giant salamander iridovirus (CGSIV)-LY isolate, genetic variation of mcp from different CGSIV isolates in China and the evolution of CGSIV.The complete DNA of mcp from CGSIV-LY strain was cloned through PCR amplification and then the molecular characteristics of mcp were studied by means of bioinformics software, and phylogenetic tree was constructed by genetic distances. The length of the mcp gene,encoding 463 aa, was 1392 bp,The molecular weight was 50.03 ku and the isoelectric was 5.75.The protein is hydrophobic with no signal peptide and transmembrane regions.The antigenicity of the protein was good.According to the protein structure prediction,there were 8 N-glycosylation sites,17 O-glycosylation sites and 20 phosphorylation sites.The secondary structure of this protein consisted primarily of a 11.23% alpha helix, with a 31.11% strand chain and random coil 57.66% without β folding,which contains three domains:the amino acid N terminal,the amino acid C terminal,capsid_NCLDV conserved domain including a low complexity region.The results of homologous comparison of amino acid sequences and evolutionary tree indicated that there was little genetic variation among mcps from different CGSIV isolates in China, and that these isolates were clustered as an independent branch in Ranavirus with parallel relationship.The protein of mcp from different isolates of CGSIV with little genetic variations should possess consistent molecular characteristics and structure.