Abstract: During 2016 and 2018, investigations were carried out on Tangpu Reservoir basin, especially on plantation of young Torreya grandis ‘Merrillii’ on non-point source nitrogen input in the reservoir. The nitrogen input in Tangpu Reservoir was simulated by SWAT model, the key areas of non-point source pollution in upstream and the landuse type which contributed the most to the nitrogen input were identified. The runoff plot experiment was implemented in young T. grandis ‘Merrillii’ plantation. The water quality data of runoff plot experiment and upstream river sections were used to calibrate the simulation results of the contribution of T. grandis ‘Merrillii’ plantation on nitrogen input in the SWAT model. The result of SWAT model simulation showed that young T. grandis ‘Merrillii’ plantations was the key areas of non-point source nitrogen pollution in Tangpu Reservoir basin. 6% of the total basin area contributed 45% of nitrogen input into Tangpu Reservoir.