Peroxidasin plays unique role in the formation and stability of extracellular matrix (ECM) in animal kingdom, however it was only characterized in Diptera, not in other insect orders. In this study peroxidasin (CsPxd) was first identified and characterized from Chilo suppressalis, a lepidopteran pest. CsPxd cDNA with a 4080 bp open reading frame encodes a peptide of 1359 amino acids, the derived amino acid sequence of CsPxd harbors the typical structural characteristics of peroxidasin family in heme peroxidase superfamily, including the signal peptide at N-terminal, leucine-rich repeat domain, Ig-loop motifs and peroxidase domain, signifying the extracellular location of protein and the involvement in ECM formation. Eukaryotic expression reveals CsPxd protein display peroxidase activity on H2 O2 , justifying the membership of peroxidase. Phyletic analysis shows the monophyletic evolution pattern of peroxidasin in insect phyle, and more over only one peroxidasin is present in each species of insects, suggesting its evolutionary conservation on function. Peroxidasin mRNA is mainly expressed in egg and the final instar larvae stage. Injection of peroxidasin dsRNA into the final instar larvae impacts the cuticle sclerotization during the metamorphosis from larvae to pupa, and eventually lead to lethality of larvae and pupa. These results suggest the presence of collagen crosslink in chorion and cuticle of insect, and indicate peroxidasin play a role in the development of chorion and cuticle, furthermore peroxidasin might be the one of potential target genes for pest control using RNAi. This article is protected by copyright. All rights reserved.,This article is protected by copyright. All rights reserved.