The cytochrome P450-dependent monooxygenases play an extremely important role in metabolic system involved in the catabolism and anabolism of xenobiotics and endogenous compounds. According to the predicted P450 sequences from the genome of Bombyx mori, a pair of primers was designed and a novel gene named CYP6AE22 was successfully cloned from the midgut mRNA of Bombyx mandarina by RT-PCR (GenBank accession number: FJ843077). Sequence analysis revealed that this gene contains a 1551 bp ORF, encoding a protein of 516 amino acids. The predicted molecular weight and isoelectric point of this protein was 60 kD and 9.0, respectively. The results of semi-quantitative RT-PCR showed that this gene was highly expressed in fat body and brain. And the expression level could be increased by induction with cypermethrin. Treatment with 5ng/uL cypermethrin could increase the expression level in midgut and fat body of the larvae of 1.5 fold and 2.5 fold, respectively. It is inferred that CYP6AE22 gene may be involved in detoxification of insecticide in Bombyx mandarina.