Nitrification potentials in micro-environment were examined in a non-planted vertical flow constructed bed system with an air pipe. The results showed that nitrification potential was significantly correlated with the dissolved oxygen inside the system. Enhanced nitrification of 10.15 g/m²·d was achieved, twice as much as the 4.71 g/m²·d obtained in the traditional one. Atmospheric oxygenation by the air pipe was a remarkable 23.7 g/m²·d, which improved the aerobic micro-environment for extra nitrification. Passive atmospheric oxy- genation, which was increased by the air pipe without energy consumption, stimulated the growth of nitrify- ing bacteria and provided favorable habitats of bacterial richness. This results in high nitrification potential in the constructed bed, which is good for high-concentration rural wastewater treatment.