Abstract: The variation of mRNA gene expression is an important pyrethroid insecticide resistance mechanism in Tetranychus urticae. To identify the molecular mechanism for producing detoxification enzymes in T. urticaein response to fenpropathrin, the mRNA expression levels of glutathione s-transferases (GSTs), cytochrome (P450s) and carboxyl/cholinesterases (CCEs) genes in laboratory fenpropathrin susceptible (SS), fenpropathrin resistant (Sp-R) and field strains (LZ-R, GN-R, WW-R, TS-R and LX-R) of T. urticae were measured using quantitative real time PCR (qRT-PCR). The results showed that relative expression levels of different detoxification enzyme genes varied with different strains of T. urticae. Compared with the SS strain, the expression levels of TuGSTd05 in the WW-R and TS-R strains, TuGSTd01 and TuGSTd06 in the LX-R strain were significantly up-regulated,1.42-2.34 times greater than the SS strain, while TuGSTd04 in the GN-Rstrain, TuGSTd05 and TuGSTd09 in the LX-R strain were significantly down-regulated, 0.41-0.70 that of the SS strain. The expression levels of P450s genes CYP406A1 and CYP4CL1 in the LZ-R, GN-R and WW-R strains were significantly up-regulated, 1.80-4.88 times that of the SS strain. The expression level of P450s genes CYP387A1 in the LZ-R strain was also significantly higher (2.19 times) than the SS strain whereas that in the LX-R strain was significantly lower (0.42 times) than the SS strain. Similarly, the expression levels of CCEs gene TuCCE-35 in the WW-R and TS-R strains was significantly higher than the SS strain. However, the gene expression levels of TuCCE-36 did not change in all strains. The significant up-regulation or down-regulation of detoxification enzyme genes (GSTs, p450s and CCEs) among different strains of T. urticae may be associated with the formation of resistance to fenpropathrin.