The aim of this project is to investigate the effect of Isoniazid drug adsorption on the geometrical and electrical structure of pristine and Ni-doped Gallium Nitride Nanotube (GaNNTs). For this purpose, 24 different geometrical configuration models are considered for adsorbing Isoniazid on the surface of nanotube and then all considered structures are optimized by using Density Function Theory (DFT) at the Cam-B3LYP/6-31G (d) level of theory. By using optimized structures, the structural parameters such as bond length and bond angle; HOMO and LUMO orbital; Density of State (DOS) plots; Natural Bonding Orbital (NBO); quantum parameters; Atom in Molecule (AIM); and Molecular Electrostatic Potential (MEP) are calculated and all the results are analyzed and discussed. The results revealed that doping Ni atom and adsorbing Isoniazid molecule decrease the energy gap and global hardness of nanotube and thereby increase the electrical properties of system. This property is suitable for making nano sensors drugs. At all adsorption models, the values of adsorption energy is negative and show that the adsorption process is exothermic and stable in thermodynamic approach. Comparing the thermodynamic properties demonstrate that Ni doping decreases the Isoniazid adsorption on the surface of nanotube; and therefore, the adsorption of Isoniazid on the surface of Ni-doped models is not as favorable as pristine models. In addition, the adsorption of Isoniazid on the surface of nanotube is physical adsorption.