Abstract: In order to study nitrogen removal process of treatments for the slightly contaminated water on hybrid constructed wetlands, three indicators including nitrogen concentration, bacteria quantity and intensity of nitrification/denitrification were analyzed in the Dengbeiqiao wetland system. Meanwhile, the process of nitrogen variation and the removal rate were discussed. The results showed that the concentration of NH₃-N and TN stepwisely decreased in this hrbrid system of oxidation pond-surface flow-subsurface flow-surface flow wetland. Removal rates of NH₃-N and TN reached for 53.24% and 48.21% in average respectively. Intensity of nitrification in the oxidation pond and in the surface flow wetland were much higher than those in the subsurface flow wetland; The final surface flow wetland owns the greatest amount of nitrate bacteria (93.00×10^5g-1) and the highest intensity of nitrification (8.42×10^2mg/(m³·h) in the surface soil); while DO on the subsurface flow wetland is the lowest, and intensity of denitrification in the surface and the deep soil reached for 32.70×10^2and 32.09×10^2mg/(m³·h), respectively. The primary unit of denitrification on hybrid constructed wetlands is the subsurface flow wetland.