In this paper, by using of density function theory (DFT), we have investigated the interaction and adsorption of Cd+2 ion on the interior and exterior surface of pristine, C, P and C&P doped BNNTs. The calculated results indicate that the adsorption of Cd+2 is exothermic and is strong electrostatic type. Inspection of quantum, natural bond orbital (NBO) and reduced density gradient (RDG) results confirm that the pristine and doped BNNTs are a good candidate to making sensor and adsorbent of Cd+2 in biological and environmental system.