In the present work, using generalized gradient approximation (GGA) in accordance with the Perdew-Burke-Ernzerhof (PBE) functional we studied the adsorption of three harmful gas molecules namely ammonia (NH3), nitrogen dioxide (NO2) and phosphine (PH3) on the surface of the bismuthene nanotube (BiNT). We studied the response of BiNT as a chemi-resistor sensor for NH3, NO2 and PH3 gas molecules with regards to three essential features, namely energy gap variation, Bader charge transfer as well as the adsorption energy. Our results demonstrate that BiNT can indeed be successfully used as a chemical nanosensor for detection of NH3, NO2, and PH3 molecules.