In this research, the effects of interaction cyanide ion (CN−) with the pristine and Ge-doped aluminum phosphide nanotube (AlPNTs) are investigated using density functional theory (DFT). At first step all considered configuration models are optimized at the B3LYP/6-31G(d) level of theory. From optimized structures the structural, electrical, NMR parameters, quantum descriptors such as global hardness, global softness, electrophilicity, gap energy, Fermi level energy, electronic chemical potential, electronegativity, natural bond orbital (NBO) and molecular electrostatic potential (MEP) of all models are calculated and results are analyzed. The negative values of Eads reveal that the adsorption process of all models are exothermic, physisorption energetically favored, and spontaneous. Inspections of results demonstrate that the adsorption of CN− on the exterior surface of pristine AlPNTs is stronger than on the exterior surface of Ge-doped AlPNTs. The NBO results indicate that the E(2) values of interaction between of (σAl−P) as donors and some σ* or n* orbitals as acceptors orbital at the all Ge-doped models are lower than those pristine models. The MEP results indicate that the positive potential is localized on Al atoms and it seems that these atoms are suitable sites for nucleophilic attack of CN−.