Atmospheric nitrogen (N) deposition includes wet and dry deposition of both inorganic and organic, or dissoluble and particle N forms. For agricultural ecosystem, atmospheric N deposition is an important way by which the lost N from the soil-plant system goes back to the agricultural fields. Whereas increasing atmospheric N deposition may not only affect human and ecosystem health, greenhouse gas balance and biodiversity, but also become one of the important causes of surface water eutrophication. Since the beginning of this century, the atmospheric N deposition and its effects on agricultural land, forestry, grasslands, watershed and city ecosystems were all conducted in China. However, information on the magnitude and environmental impact of N deposition in China is still limited. Danjiangkou Reservoir, which locates where the Hubei and Henan provinces meet and has a drainage area of 95200 km², is the source of water for the Middle Route Project which is part of the South-to-North Water Transfer Scheme. Recent monitored results showed that, high concentration of total N in some branch catchment rivers is one of the main water environment problems facing Danjiangkou Reservoir. However, the atmospheric N deposition and its effects on water quality in this area are not clear. In this study, the atmospheric N deposition in Danjiangkou Reservoir area of northwest Hubei province from 2009 to 2011 was monitored. Results showed that, the monthly averaged concentration of total nitrogen (TN) in bulk atmospheric deposition ranged from (3.70±0.89) mg/L to (10.36±10.68) mg/L,which was significantly negatively correlated to the corresponding monthly rainfall (R=－0.592^{* *},n=32). The seasonal averaged concentration of TN was ordered as: Winter ((8.21±2.71) mg/L) > Spring ((3.94±1.99) mg/L) > Autumn ((3.23±1.52) mg/L) > Summer ((2.70±0.72) mg/L). The annual averaged concentration of TN was (3.70±0.93) mg/L. The bulk atmospheric TN deposition rates from 2009 to 2011 averaged (26.53±5.44) kg/hm², among which the dry deposition rate was (7.80±1.23) kg/hm² or 29.4%, and the wet deposition rate was (18.73±4.20) kg/hm² or 70.6%. The seasonal percentage of TN in bulk deposition was ordered as: Summer ((31.2±6.2)%) > Autumn ((29.9±12.3)%) > Spring ((28.5±11.6)%) >> Winter ((10.4±4.2)%). In the atmospheric dry deposition, NH₄⁺-N, NO₃^--N, dissoluble organic nitrogen (DON) and particle nitrogen (PN) in TN accounted for 22.1%, 16.8%, 37.2% and 23.9%, respectively. In the atmospheric wet deposition, NH₄⁺-N, NO₃^--N, DON and PN in TN was 36.6%, 34.4%, 12.9% and 16.1%, respectively. The above results may serve as a scientific basis for agricultural field fertilization, ecosystem environment treatment and water resource protection in Danjiangkou Reservoir area, as well as for the study on spatial and temporal variations of atmospheric N deposition in China.