Abstract: Soil moisture conditions regulate nitrogen transformation and the effects of nitrogen deposition.However, the effect of nitrogen deposition on nitrogen transformation is not very clear under saturation water holding capacity condition.Therefore, in order to investigate the effects of different nitrogen deposition on soil net nitrogen transformation and N₂O emission under saturation moisture capacity condition, using zonal red soil collected from Wuyi Mountain in mid-subtropical forest, a 14-day simulative experiment in the laboratory was carried out under 110% water holding capacity condition with different nitrogen forms((NH₄) ₂SO₄, NaNO₃ and NH₄NO₃) and levels(0(CK), 20.0(LN) and 66.7(HN) mg/kg).The results showed that(NH₄) ₂SO₄ and NaNO₃ treatments had little effect on soil net nitrogen mineralization compared with CK.The net nitrification was negative in(NH₄) ₂SO₄ treatment at the high nitrogen level, which illustrated that nitrification was quite weak, while the net ammonification was higher than other treatments especially in NaNO₃ treatment.This phenomenon was probably due to the occurrence of dissimilar reduction of nitrate to ammonium(DNRA).The net nitrification was increased significantly, and the soil soluble organic nitrogen(SON) was reduced dramatically in the NaNO₃ treatment.The soil ammonium and nitrate nitrogen were reduced simultaneously in the NH₄NO₃ treatment, demonstrating the immobilization of N, and a higher soil microbial biomass nitrogen(MBN) was observed at high nitrogen level than at low nitrogen level.The rate and cumulative amount of soil N₂O emission in both the NaNO₃ and NH₄NO₃ treatments were obviously higher than CK, and these effects were much greater at high nitrogen level than at low nitrogen level.The soil N₂O emission in the(NH₄) ₂SO₄ treatment was almost equal to that of CK, and the cumulative amount of soil N₂O emission was lower at high nitrogen level compared with that of low nitrogen level.Taken together, we concluded that, under saturation water holding capacity condition, mixed nitrogen form may have greater effect on soil nitrogen transformation pattern, and nitrogen in form of NO₃^- significantly promoted the soil N₂O emission especially at high nitrogen level.These results provide useful information when assessing the effect of different deposited nitrogen forms on soil nitrogen transformation under precipitation circumstance.