In order to explore the possible target and mechanism of flufenoxuron, important agricultural pests Locusta migratoria manilensis and Oxya chinensis were used as test insects in this study. A partial fragment of chitin synthase 1 cDNA from O. chinesis (OcCHS1) was amplified using a pair of degenerate primers. With the mid-2nd instar nymphs of O. chinesis and the 1st, 2nd, 3rd instar nymphs of L. migratoria manilensis dipped in flufenoxuron as treatments and acetone treatment as the control, the effects of flufenoxuron on the mRNA expression of chitin synthase genes were analyzed using RT-PCR and real-time quantitative PCR. The partial cDNA fragment of OcCHS1 (GenBank accession number: HM214491) was obtained, which consists of 312 nucleotides that encode 104 amino acid residues. The deduced amino acid sequence of OcCHS1 showed 95% identity with those of LmCHS1. The results of RT-PCR and real-time quantitative PCR analysis showed that the expression of OcCHS1 in the mid-2nd instar nymphs of O. chinesis and LmCHS1 in the 1st, 2nd and 3rd instar nymphs of L. migratoria manilensis exposed to flufenoxuron increased 102%, 34%, 82% and 89%, respectively, compared to the control. Increased expression of CHS1 mRNA may be due to compensation response of the CHS1 gene at the transcriptional level that is caused by the retarded chitin synthesis. It is so inferred that chitin synthase may be one of targets of flufenoxuron.