Classification of esterase isozymes of the apterous green peach aphids (Myzus persicae Sulzer) collected in tobacco fields were investigated by the native polyacrylamide gel electrophoresis (PAGE). A total of twelve esterase bands were identified in adult apterous aphid, and the difference of enzyme band activity in the clones was observed at the first and second bands group. Esterases of green peach aphids reacted with specific substrate were more stained $alpha$-naphthyl acetate than $alpha$-naphthyl propionate, and $alpha$-naphthyl acetate more than $eta$-naphthyl acetate. Twelve esterases on the basis of inhibition by the three types of inhibitors (organophosphates: 2.5$ imes$10$^{-3}$ M paraoxon, 4$ imes$10$^{-3}$ M DFP; eserine sulfate : 2$ imes$10$^{-3}$ M eserin; sulfhydryl reagents: 2$ imes$10$^{-3}$ M p-HMB) were classified into three class, namely, cholinesterase (ChE) I, II, carboxylesterase (CE) and arylesterase (ArE), and these classes contained 3, 4, 3 and 2 isozymes, respectively.