Abstract: 【Objective】 This study aimed to understand the genetic diversity of the Bombyx mori nucleopolyhedrovirus (BmNPV) strains in sericultural regions of Longchuan County,Dehong Prefecture,Yunnan Province, and provide reference for the origin of Yunnan BmNPV and the scientific prevention and control of B. mori nuclear polyhedrosis.【Method】 The lef-8 gene of BmNPV isolate from B. mori in the sericultural regions of Longchuan County,Dehong Prefecture, Yunnan Province was cloned and analyzed based on bioinformatics through online software including ExPASy,SignalP 5.0, TMHMM 2.0,NetOGlyc,NetPhos 2.0 and SWISS-MODEL. Then neighbor-joining(NJ) method of MEGA 7.0 was applied to constructa phylogenetic treeon the basis of the similarity of lef-8 gene nucleotide sequence.【Result】 The whole length of lef-8 gene nucleotide sequence of BmNPV-YNLC strain from sericultural regionsof Longchuan County,Dehong Prefecture,Yunnan Province was 2631 bp,which encoded 876 amino acid residues. The encoded protein(LEF-8) had neither signal peptide sequence nor transmembrane domain,with the molecular weight of the protein being 101.63 kD and the theoretical isoelectric point(pI) 8.8. The amino acid residues from 750 to 800 showed high hydrophobicity,and some amino acid sites showed hydrophilicity,high antigenic index and surface accessibility. The amino acid sequence of the protein contained 6 potential N-glycosylation sites and 62 phosphorylation sites(25 serine phosphorylation sites,23 threonine phosphorylation sites and 14 tyrosine phosphorylation sites), but did not have O-glycosylation sites. The similarity of lef-8 gene nucleotide sequence from BmNPV-YNLC strain and BmNPV-T3 strain was 99.7%. The lef-8 gene of BmNPVYNLC strain had three base(CAA) deletionat positions 96-98,and there were two nonsynonymous mutations(⁶⁴⁶T→A and ¹⁸⁹⁵C→G) and seven synonymous mutations in the nucleotide sequence. The phylogenetic tree constructed via lef-8 gene nucleotide sequence similarity suggested that the genetic relationship between BmNPV-YNLC strain and BmNPV from Japan and South Korea was close,while that between BmNPV-YNLC strain and BmNPV from China was far.【Conclusion】 The lef-8 gene is highly conserved in BmNPVs strains from different regions. BmNPV-YNLC strain is closely related to BmNPV from Japan and South Korea, but there is amino acid amine deletion and mutation in its LEF-8 protein N-terminal, which indicates that BmNPV-YNLC is a new popular strainin Yunnan sericultural regions.