A field experiment, directed against non-point source pollution brought about by nitrogen leaching from paddy field in Taihu Lake region, was conducted to study effects of nitrogen management on on nitrogen leaching from paddy field at depths of 20~40 cm, 40~60 cm, 60~80 cm and 100~120 cm. The experiment was designed to five patterns of nitrogen management, i.e. Case-specific nitrogen application (CSN), Organic & chemical N combined application (OCN), Controlled release urea application (CRU), Reduced chemical N application (RCN) and Farmer’s common N application (FN). It was found show that in the soil layer (20~40 cm), TN in the leachate was positively related to N application rate depth, and CRU has more TN leakage amount. Compared with the other treatments, FN treatment had a higher concentration at 40~60 cm than 20~40 cm depth. DON was the prime form of N leaking into ground water floor. NH4+-N concentration would decrease 37%~50% if N input was reduced by 33%. Thus it can be seen that reduced N input and use organic N with chemical N would be environment-friendly nitrogen management methods for Taihu Lake region.