Abstract: In order to investigate the chemical components characteristics and acidification trend of precipitation at Nanhai District, the cross-border region of Guangzhou and Foshan, the precipitation samples were collected during January to December of 2016. The pH, conductivity and ionic composition of precipitation were analyzed. Results indicated that the annually averaged pH, conductivity and total ion concentration were 5.05, 19.4 μS/cm and 6.41 mg/L, respectively. The acid precipitation pollution of Nanhai District in 2016 had improved, but the frequency of acid precipitation was as high as 63.1%, and the extent of acidification was still relatively high. The N ${\mathrm{O}}_3^{-}$ and S ${{\mathrm{O}}_4}^{2-}$ which were contributed by the artificial sources played the major roles in the acidification. By analyzing the S/N ratio, it was found that N ${\mathrm{O}}_3^{-}$ had exceeded S ${{\mathrm{O}}_4}^{2-}$ and become the primary acid factor of precipitation in Nanhai District.