Abstract: Subcellular distribution of carboxylesterase (CarE) activities and the properties of CarE were investigated in diamondback moth (DBM), -Plutella xylostella,- collected from Xuanhua, Hebei Province, Wuhan, Hubei Province, Kunming, Yunnan Province, Beijing city, AVMs-selected resistance strain and susceptible strain in 1997. There was not significant difference of subcellular distribution of CarE activity among the susceptible strain and the resistant populations or strain. The major portion (34%52%) of CarE activity was associated with mitochondria fraction and a little (7%16%) with microsome fraction among four fractions in all populations tested. The CarE activity in mitochondria fraction of resistant populations was higher than that of susceptible strain. The affinity of CarE in supernatant fraction toward α-naphthyl acetate (α-NA) was highest among four fractions and no difference in all populations tested. The affinity of CarE in mitochondria fraction toward α-NA was lowest among four fractions in Yunnan, Beijing, Wuhan and Xuanhua populations. The affinity of CarE in mitochondria fraction toward α-NA was AVMs-selected strain (F 16 ), Yunnan, Wuhan, Taiwan susceptible strain, Xuanhua, Beijing population in order of decrease.