Fluxes of atmospheric wet deposition of nitrogen and precipitation chemical composition were measured from July 2002 lo June 2003 at the lakeside of Lake Taihu, on the Taihu Station, Tuoshan Island, Dongshan Station, and Wuxi, Suzhou, Huzhou, Changzhou sites. Results show that TN concentration of atmospheric wet deposition ranged from 2.06(Changzhou site) to 3.71 (Tuoshan Island site) and atmospheric wet deposition in the valley of Lake Taihu shows eutrophication. The wet deposition rale (F_w) of TN, NH₄⁺-N, NO₃^--N, TIN, TON between atmosphere-water interfaces were measured, and the annual average F_w of TN, NH₄⁺-N, NO₃^--N, TIN, T0N was 2806.75 kg/km², 1458.81 kg/km², 631.67 kg/km², 2090.48 kg/km² and 716.28 kg/km², respectively. The direct input of TN f NH₄⁺-N, NO₃^--N, TIN, TON through atmospheric wet deposition is 6562.2t, 3410.7t, 1476.8t, 4887.5t, 1674.71, respectively.and accounts for 13.59% of the total of the aquatic ecosystem of Lake Taihu.. TIN dominated in TN, accounting for 78.78% of TN. The variation of TIN wet deposition rate showed a seasoned seasonal feature:it was higher iu summer, nexl in spring, find lowest in winter and autumn. This phenomenon may potentifdly accelerate the cyanobacterial bloom and the eutrophication process of the water body of Lake Taihu.