Sea salt particles containing NaCl are among the most abundant particulate masses in coastal atmosphere. Reactions involving sea salt particles potentially generate Cl radicals, which are released into coastal atmosphere. Cl radicals play an important role in the nitrogen and O3 cycles, sulfitr chemistry and particle formation in the troposphere of the polluted coastal regions. This paper aimed at .the heterogeneous reaction between gaseous HNO3 .and solid NaCl. The mech.anis.m was in.vestigatedby density functional theory (DFT). The results imply that water molecules induce the surface reconstruction, which is essential for the heterogeneous reaction. The surface reconstruction on the defective (710) surface has a barrier of 10.24 kcal.mol-1 and is endothermic by 9.69 kcal.mol-1, whereas the reconstruction on the clean (100) surface has a barrier of 18.46 kcal.mol-1 and isendothermic by 12.96 kcal.mol-1. The surface reconstruction involved in water-adsorbed (710) surface is more energetically favorable. In comparison, water molecules adsorbed on NaCl (100) surface likely undergo water diffusion or desorption. Further, it reveals that the coordination number of the Cl-out is reduced after the surface reconstruction, which assists Clout to accept the proton from HNO3. HCl is released from heterogeneous reactions between gaseous HNO3 and solid NaCl and can react with OH free radicals to produce atomic Cl radicals. The results will offer further insights into the impact of gaseous HNO3 on the air quality of the coastal areas.