Abstract: Due to the serious trend of water pollution across the country, the problem of aquaculture wastewater discharge must be solved appropriately to achieve sustainability. As a novel technology for sewage treatment, constructed wetland (CW) has been gradually expanded to aquaculture. In view of the disadvantages in land dispute with pond aquaculture, how to develop or design a land-saving, high-efficiency CW will be the focus of future study. It is widely accepted that artificial aeration can enhance the purification efficiency of CW's subsurface flow on wastewater due to its capacity to improve the oxidation conditions, which is beneficial for organic matter degradation and nutrient removal. Nevertheless, more detailed studies on the impact of aeration intensity on treatment performance and the associated relationships with influencing factors are still lacking. In the present study, 7 pilot-scale vertical-flow CWs with different combinations of substrates and plants were configured and then systematically investigated in field for treating low-strength aquaculture wastewater with or without artificial aeration. An attempt to explore the impact of the aeration on nitrogen (N) removal or transformation within wetland bed was made. After a thorough comparison between aerated and non-aerated states investigated simultaneously or by stages, the results were depicted as follows: under the operating conditions characterized by high hydraulic loading(HLR) (mean value 1.85 m/d), short hydraulic retention time(HRT) (mean 4.6 h), strong aeration intensity (air flow rate 30 m3/(m2·d), air-water ratio 16.2:1) and low inflow dissolved oxygen (DO) (mean 2.34 mg/L), nitrification occurred obviously within all the systems no matter with or without aeration. DO replenished from atmospheric reoxygenation and plant roots appeared enough to cover the quantity consumed by nitrification and organic matter degradation. Artificial aeration enhanced the intensity of internal mineralization and nitrification. In virtue of no lack of available carbon source (for instance in the present case, the influent ratio of chemical oxygen demand to nitrogen (COD/N) ranged from 28.4 to 30.6), the probability for denitrification under the aerated state increased compared to the non-aerated state, which finally led to the elevation of purification performance on total N (TN). Nevertheless, if too much DO was presented under the aerated state, denitrification would further be restrained, which would conversely lead to the reduction of removal efficiency on TN. Therefore, for complete-drain vertical-flow systems, it is not the truth that the higher aeration intensity is, the better efficacy will be obtained. To obtain higher stable purification efficiency, a good suggestion is decreasing HLR or extending HRT or supplementing horizontal flows to vertical-flow systems to ensure complete denitrification. That strategy will be especially beneficial for TN removal.