[Aim] Spodoptera litura larvae are polyphagous and voracious pest. The intestinal microorganisms treated with methyvitamin salt were compared to characterise the metabolic changes of intestinal symbiotic microflora exposed to toxicants and the correlation between the metabolism of the strain and the receptor of methyl salt.[Method] The midgut of S. litura larvae collected from the experimental field of Danzhou Agricultural Science Base in Hainan Province was dissected in the laboratory with or without emamectin benzoate immersion. The 16S rRNA variable region of bacteria in the midgut of S.litura larvae fed on methyl salt vs. non-methyl salt was sequenced on Illumina MiSeq sequencing platform with high through put to analyze the diversity of bacterial community structure.[Result] Enterobacter and Rhizobium were dominant but their abundance decreased significantly after treatment with methyl salt. In addition, significant changes were observed in Serratia and Xanthomonas, with a decline almost to zero after treatment. The abundance of Corynebacterium and Methylobacterium, which not previously dominant, increased significantly after treatment.[Conclusion] The dominant microflora and richness of S. litura treated with methyl salt were different after treatment, suggesting that the structure of intestinal microflora in S. litura larvae might be related to the toxicity mechanism of emamectin benzoate.