[Objective]Mt. Dinghu National Nature Reserve,located in Guangdong Province,is a transitional zone of tropics and subtropics. It provides a unique and important opportunity for climate change studies. The change of precipitation pattern affects the microclimate within a regional forest ecosystem. The research on the characteristics of hydrogen (deltaD) and oxygen (delta~(18)O) stable isotope in precipitation and the source of regional atmospheric precipitation are theoretically and practically important to understand the water cycling and community succession in the forest ecosystem of Mt. Dinghu,and wisely use and manage regional water resources. [Method]The precipitation deltaD and delta~(18)O data in the period from August 2013 to August 2014 were analyzed to examine the relationship between the characteristics of deltaD and delta~(18)O and their environmental factors. Furthermore,the air mass transmission pathway was determined and the regional water vapor sources were identified based on HYSPLIT model. [Result]The meteoric water line equation is deltaD = 7.863delta18 O + 9.664 (R~2 = 0.975,n = 108); the average deltaD value is - 34.44,ranging from - 118.26 to - 15.52,and the average delta~(18)O value is - 5.58,ranging from - 16.05 to 2.25. The atmospheric precipitation excess deuterium (d) follows a seasonal pattern with low value in winter and high value in summer. Aprecipitation effectexists significantly whereas thetemperature effectis not obvious. [Conclusion]There are obvious seasonal changes of deltaD and delta~(18)O in atmospheric precipitation in Mt. Dinghu. In dry season,the air mass mainly comes from North China and Eurasia,as well as local evaporation, while in the wet season,the air mass mainly comes from the western Pacific Ocean,the South China Sea,and the Indian Ocean.