[Aim] Pachypeltis micranthus is a specialist herbivore feeding on the invasive plant Mikania micrantha. CYP4 family genes play a very important role in the interaction between insects and host plants.[Method] A cDNA encoding CYP was cloned using rapid amplification of cDNA ends (RACE) strategy. Fluorescence quantitative real time PCR (qPCR) was used to detect the expression of CYP gene in different body parts.[Result] PmCYP4 gene was 1713 bp in full length, and 1500 bp in ORF, which encoded 500 amino acids with a predicted molecular weight of 57.44 ku. There was no signal peptide in this deduced amino acid sequence. The homology of PmCYP4 of P. micranthus with CYP4 family of other insects was more than 40%, with the closest relationship with CYP of Cimex lectularius. PmCYP4 gene was expressed in different body parts with the highest expression in leg. The expression in wings of males was significantly higher than in antennae and residue and 2.37 times higher than females, but there were no significant differences in these body parts for females.[Conclusion] In addition to metabolic toxins, the main function of PmCYP4 gene may be to encode for enzymes related to the movement of P. micranthus.