A computational study, density functional theory (DFT) have been applied on the adsorption of DDD, DDE and DDT molecules on (8,0) pristine single-walled carbon nanotubes (PSWCNTs). The DDD, DDE and DDT molecules adsorption are aggressively favorable with adsorption energy (E_ads) equal to -67.266, -58.776 and -52.245 eV respectively. In this study, the electronic properties analysis reveals that the physisorbed DDD, DDE and DDT are changing the highest occupied molecular orbital (HOMO) energy gap and lowest unoccupied molecular orbital (LUMO) energy gap of carbon nanotubes which have been reduced after interaction with these molecules from 0.519 eV to 0.356, 0.289 and 0.296 eV respectively. These three insecticide molecules make changes outside of the carbon nanotube to the set of energy molecule and thus nanotubes are obtained as conductive structure. As inference it reveals that the pristine single-walled carbon nanotubes can be a good sensor for the detection of DDD, DDE and DDT molecules.