Abstract: ObjectiveEffects of nitrogen element in fast-growing eucalyptus on water quality of drinking water sources were studied to provid scientific references for prevention and control of pollution from fast-growing eucalyptus planta-tion in drinking water sources in Guangxi. MethodTaking Liulan reservoir drinking water source in Hengxian county, Guangxi as an example, the water quality at water intakes was analyzed. During rotation period of 5 years(2011-2015), taking Liulan reservoir catchment area as the research scale,fertilizer application situation in the villages within catchment area were investigated,the amount of fertilizer and emission of pollutant nitrogen were estimated,the correlation between nitrogen emissions and water pollution factors were analyzed. ResultResults indicated that except the first year(2011), the data in four years(2012-2015) failed to reach class II water standard. Ammonia nitrogen data in five years did not achieve class II water standard. The total nitrogen emission of eucalyptus forest non-point source in catchment area ac-counted for 84.7% of total nitrogen pollutant emission in basin perimeter. Total nitrogen emission induced by fast-growing eucalyptus fertilization was significantly correlated with total nitrogen monitoring data(α=0.05, P=0.023), whereas it was not significantly correlated with ammonia nitrogen monitoring data (α=0 . 05 , P=0 . 106 ) . Total nitrogen emissions from domestic pollution sources and decentralized poultry breeding pollution sources were significantly correlated with ammonia nitrogen monitoring data(α=0.01, P=0.009),but were not significantly correlated with total nitrogen monitoring data(α=0.05, P=0.072). ConclusionThe main pollution source of nitrogen element in Liulan reservoir drinking water source is fertilization for fast-growing eucalyptus plantation. Total nitrogen concentration is affected by total nitrogen emission from fertilization to a certain extent. Therefore, adopting formula fertilization by soil testing, controlling and arranging fertilizer dosage and times can reduce nitrogen emission and prevent water in water sources from eutrophication.