Abstract: DFT method has been carried out to studying the effects of NH3, SO2, CO2, O2 and CH3 on the nanotube (2, 2) using the B3LYP functional and the 3-21 G basis set, the optimization structure, properties such as Ionization potential (I), Electron affinity (E), Energy gap (Eg), thermal properties (Eth, CV and S), EPS and IR spectra. The CNTs (1 and 2) is semiconductor with Eg ranging from 0.98-0.90 eV. All properties are calculated by using Density Function (DFT) method with basis set 3-21 G.