To determine the optimal ammonia nitrogen loading in intensive pond aquaculture systems，an outdoor simulation experiment was conducted using Vallisneria as the model plant.The nitrogen removal performance of the Vallisneria-based aquatic system was evaluated under continuous inputs of varying nitrogen loads by analyzing nitrogen removal characteristics in both the overlying water and sediment pore water.The nitrogen removal capacity of Vallisneria was quantified，and the effects of ammonia nitrogen loading intensity on nitrogen purification performance were elucidated.Three levels of ammonia nitrogen loading were examined.The results showed that under low ammonia nitrogen loading，both the Vallisneria group and the control group （without macrophytes，No-plant group） achieved nitrogen removal rates of approximately 90%.Under medium ammonia nitrogen loading，the nitrogen removal capacities of both the Vallisneria natans group and the No-plant group decreased.The total nitrogen removal rate of the V. natans group ［（70.00±0.42）%］ was slightly higher than that of the No-plant group ［（64.66±0.27）%］.Ammonium nitrogen accumulated in the overlying water of both groups，but the concentration in the V. natans group was lower.Under high ammonia nitrogen loading，the total nitrogen removal rates of the V. natans group and the No-plant group decreased to （33.63±0.37）% and （33.17±0.23）%，respectively.The ammonium nitrogen concentration in the overlying water of both groups increased rapidly，with no significant difference between them.However，under all nitrogen load conditions，the concentration of ammonium nitrogen in the sediment interstitial water of the V. natans group was lower than that of the No-plant group.Calculation of of V. natans’s contribution to nitrogen removal indicated that under low and medium ammonia nitrogen loads，V. natans exhibited a certain absorption capacity to absorb pollutants，whereas high ammonia nitrogen loads negatively impacted its nitrogen removal ability.In conclusion，controlling the exogenous ammonia nitrogen load in aquaculture water bodies to below medium concentrations （approximately 0.625 grams per cubic meter） can ensure the reduction of harmful nitrogen.