The tomato leafminer, Tuta absoluta Meyric (Lep: Gelechiidae), is a key pest of tomatoes, and if no action is taken to control this pest, it can destroy 80-100% in the greenhouse and field tomato. Two insecticides, Bacillus thurengiensis (Bt) and imidacloprid have a significant role in controlling this pest. In the present study, the effects of B . thurengiensis and imidacloprid were investigated on the life table of tomato leafminer when eggs and forth instar larvae were treated and their effect on the biochemical parameters of larvea. Also, the effect of imidacloprid on the oviposition and damage of this pest on the tomato plants was determind. For this purposes, sublethal effects of of LD 4 and LD 9 doses of B . thurengiensis and LC 10 and LC 20 doses of imidacloprid were investigated on biological and life table parameters of this pest when egg or fourth larvae was tested. To evaluate the life table parameters, the experiments were performed as 10 replicates for each sublethal dose and control. The results showed that the biological parameters including egg incubation period, male adult longevity, fecundity and preadult survival rate decreased in B . thurengiensis treatment compared to the control. While total longevity of female insects, adult pre oviposition period and total pre oviposition period of insects were increased, in B . thurengiensis treated females. In treated with imidacloprid, the egg incubation period, the preadult survival rate were decreased compared to the control but pupa and pre-adult duration were significantly increased only in treated female with LC 20 . The results also showed that although the life table parameters, including the intrinsic rate of increase ( r m ), the finite rate of increase ( ? ) and the net population increase ( R 0 ) in sublethal doses of B . thurengiensis and imidacloprid were decreased, the mean generation time ( T ) was increased in insect treated with B . thurengiensis and imidacloprid compared to the control. Gross reproductive rate decreased in LD 9 of B . thurengiensis , but this parameter was not affected by sublethal concentration of imidacloprid. Also, in the treatment of larvae of the fourth instar with sublethal doses in both insecticides, fecundity of females were significantly decreased. The evaluation of biochemical parameters showed that in 4th larvae treated with sublethal doses of B . thurengiensis , protein content increased and total proteolytic activity decreased. Also, in the 4th larvae treated with imidacloprid, the total fat content decreased. Results of evaluation effect of residual toxicity on the surface of the plants on oviposition and pest damage revealed that although the number of eggs laid on spray and non-sprayed plants was the same, the pattern of egg distribution changed on the plant and damage of pests on plants that previously sprayed was significantly reduced. In general, the results of this study showed that because of sublethal doses of B . thurengiensis and imidacloprid affected negatively fertility-life table parameters and behavior of this pest especially oviposition, they can be used to control of T. absoluta . Key words: tomato, life table, enzym activity, damage