Abstract: The activities of glutathione S-transferases (GSTs) and carboxylesterases (CarE) in Myzus persicae(Suler) fed with tobacco seedlings infected by CMV(M. persicae Ⅰ) were determined with Myzus persicae fed with healthy tobacco seedlings (M. persicae Ⅱ) as control.The results showed that there was a significant difference between GSTs specific activities in M. persicae Ⅰ and Ⅱ.Determined kinetic parameters of enzyme revealed that the Michaelis constants (K_m) value of M. persicae Ⅰwas significantly higher when using CDNB and GSH as substrates, which indicated that the affinity of GSTs in M. persicae Ⅰ to CDNB and GSH declined obviously.As for CarE, the results showed that the specific activity of CarE in M. persicae Ⅰ 0.3618 μmol/mg·min was significantly higher than that in M. persicae Ⅱ 0.1858 μmol/mg·min, and there was also a significant difference of CarE specific activity distribution between M. persicae Ⅰ and M. persicae Ⅱ.individuals.