Abstract: Employing first-principles calculations based on density functional theory, we conduct a comprehensive analysis of the adsorption characteristics of Pb and Hg on monolayer AlN, including adsorption energy, differential charge density maps, band structures, density of states, and recovery time. The results indicate that Pb adsorption on monolayer AlN exhibits a greater adsorption energy and a shorter adsorption distance compared to Hg, suggesting a stronger interaction between Pb and AlN. Furthermore, upon adsorption of Pb, the system exhibit a magnetic moment of 2 μ_B, whereas no magnetic moment is observed for the Hg-adsorbed system. This magnetic disparity offers a potential strategy for the discriminative detection of Pb and Hg. Regarding recovery time, it is found that the monolayer AlN could rapidly recover at room temperature within 35 ns after Hg adsorption, implying swift reversibility under ambient conditions. For Pb, rapid desorption is also achievable upon heating to 498 K. Therefore, as a green and environmentally friendly heavy metal sensor, monolayer AlN demonstrates significant potential in heavy metal pollution detection technologies.