Abstract: The expression pattern of Liposcelis entomophila chitin synthase 2（LeCHS2） gene and its biological function in the development of L.entomophila were studied in order to provide a theoretical basis for the prevention and control of L.entomophila and to investigate new targets for pest management. LeCHS2 was cloned and the coding sequence（CDS） of the LeCHS2 was 4 524 bp in length, encoding 1 507 amino acids. Bioinformatics software analysis found that it contained 17 transmembrane helices, the predicted molecular weight of the protein was 172.9 kDa, with a theoretical isoelectric point of 6.24 and no signal peptide. The amino acid sequence of LeCHS2 shared 49.05%-53.67% identity with CHS2 from the other 8 insects. The phylogenetic tree showed that LeCHS2 had the closest relationship with Pediculus humanus corporis CHS2. The expression patterns of LeCHS2 in different developmental stages and different tissues of Liposcelis entomophila were detected by real time quantitative PCR. It was found that LeCHS2 was primarily expressed in the midgut and hindgut, indicating that the gene mainly plays a role in the midgut and hindgut. The relative expression of LeCHS2 in numph was higher than in adults, and the highest expression was found at the 1st and 11th of the nymph stage. To study the function of LeCHS2, a RNA interference（RNAi） method was developed using dsRNA with a nano carrier formed by chitosan（CS） cross-linked with sodium tripolyphosphate（TPP）. After continuous feeding of CS-TPP-dsLeCHS2 for 24, 48, 72, and 96 h, the expression of LeCHS2 gene decreased significantly. The interference efficiency was detected by real-time quantitative PCR. The interferential efficiency of LeCHS2 after continuous feeding on CS-TPP-dsLeCHS2 for 24, 48, 72, and 96 h was 79.4%, 47.0%, 40.0% and 25.0%, respectively, and after 8 d of continuous feeding, the survival rate of L. entomophila reached 56.6%. After interfering LeCHS2, observation of the external morphology of the abdomen showed that the body length was shortened by 17%, and the abdominal thickness was reduced by 18%, and the body weight decreased significantly. Observation of tissue sections revealed that the absence of periesophageal membrane led to the exposure of intestinal epithelial cells. It showed that the function of LeCHS2 was related to the formation of midgut peritrophic membrane, which was vital for the growth and development of L. entomophila. Interfering LeCHS2 gene affects its feeding, digestion, and absorption, and thus hinders the development and causes the mortality of L. entomophila.