The isotopic characteristics of atmospheric precipitation have important implication for the water cycle, water vapor sources and climate change studies. This research analyzed temporal and spatial characteristics of stable isotopes and its influencing factors at four IAEA ’s site: guangzhou, guilin, liuzhou and Hong Kong in the Pearl River Basin. The results show that the change of δ18 O in precipitation behaves obvious low value in dry season and the high value in rainy season. Throughout the year, isotopic values at the four sites are mainly affected by temperature. In the dry season, the isotopic values of precipitation show relatively weak amount effect. The local WML is obtained: δD＝8.084δ18 O+10.998，R＝ 0.965, in the Pearl River Basin. This value is relatively close to the global and Chinese ones. This imply that the precipitation underwent the Rayleigh fractionation. The deuterium excess presented low value during the rainy season and high value during dry season, indicating that water vapor in the Pearl River Basin mainly comes from the ocean. However, this basin would be affected by the north air and local evapotranspiration vapor in dry season.