Using density functional theory (DFT) and non-equilibrium Green's function method (NEGF), we investigate the electronic structures and transport properties of hydrogenated zigzag phosphorene nanoribbon (ZPNR) after adsorption of four typical harmful molecules. The results show that SO3 and CCl4 are both tending to adsorb on the top site of hydrogenated ZPNR. The NH3 and CH4 are both tending to adsorb on a hollow site of hydrogenated ZPNR. Hydrogenated ZPNR exhibits a strong adsorption of SO3, and the corresponding adsorption energy and charge transfer are largest in four harmful molecules. Mor...