Our work highlights the functionality of a novel two-dimensional phosphorene allotrope entitled green phosphorene for inorganic gas detection for the rst time. Four inorganic molecules, NH 3 , SO 2 , HCN and O 3 , are considered as adsorbates and the adsorption conformation, adsorption energy, charge transfer, density of states, and electronic band structure are systematically scrutinized based on density functional theory. Our calculations show that the adsorption energy of O 3 on pristine green phosphorene is the lowest among the four considered gas molecules, suggesting that the substrate is more sensitive to O 3 . Signi cant changes in electronic structures con rm the possibility of green phosphorene for O 3 detection. Biaxial strains and electric elds were applied to investigate the changes in adsorption behavior. The presence of compressive strain could enhance adsorption sensitivity between O 3 and green phosphorene, while the tensile strain induces the dissociative adsorption that not suitable for reversible sensor. Furthermore, by controlling the orientation of external electric eld, it is possible to achieve O 3 adsorption-desorption cycle, which is of great signi cance for green phosphorene in the application of reversible gas sensor.