In the growing seasons of 2012 to 2013, different forms of nitrogen deposition concentrations were observed in forest throughfall in the southeastern Tibet Plateau. The results show that Total dissolved Nitrogen (TN) deposition concentrations were 8.82 kg〖DK〗·hm-2 and 6.91 kg〖DK〗·hm-2 from May to October in 2012 and 2013, respectively. NO-3N accounts for 16.98%, NH+4N accounts for 53.39% and DON (Dissolved Organic Nitrogen) for 29.63% of TN in the troughfall, respectively, indicating NH+4N had the largest contribution to the wet deposition of nitrogen. For seasonal variability, the TN deposition shows a single peak in the late and middle summer in 2012 and 2013. On the annual scale, the monthly average temperature is positively correlated to TIN (Inorganic Nitrogen) deposition (〖WTBX〗p〖WTBZ〗<0.05). Both TN and TIN depositions are positively correlated to accumulative precipitation (〖WTBX〗p〖WTBZ〗<0.01). Monthly average temperature and accumulative precipitation can account for 55.2% of the variation of the TN deposition flux in the forest thoughfall.