The research of different conditions, various forms of nitrogen in vertical flow constructed wetland filling to the vertical concentration distribution at different depth, by measuring the nitrogen removal effect, so as to determine the effective height of packing. Using zeolite and ceramic filler, lythrum salicaria consists of wetland plants of four units of vertical flow constructed wet land system. Setting the 1#: ceramic, planting, no aeration; 2#: zeolite, no plants, no aeration; 3#: zeolite, planting, no aeration; 4#: zeolite, planting, aeration. The depth of the four device at various nitrogen concentration and conversion rate was determined. The 4 processing unit average conversion rates of NH4 +-N were 87%, 89%, 89.8%, 91.6%; NO3 --N system does not reduce, but the accumulation. The 1#-4# processing unit and the average removal rates of TN were 27.9%, 25.3%, 35.1%, 19.6%. Four unit in the packing depth is 20-30cm DO decreased rapidly, to 50cm when the DO reaches the minimum, respectively 1.55mg/L, 0.71mg/L, 0.68mg/L, 5.39mg/L. The simulation system, 3# conditions on the nitrogen removal effect is best. Transformation and TN 3# unit of NH4 +-N removal in the depth reached the maximum at 30cm, so the artificial wetland effective depth of zeolite filler for 30cm. Higher concentration of NO3 --N in the four unit, the main reason is the lack of carbon source, denitrification was weaker, caused the accumulation of NO3 --N, appropriate supplementary carbon source is in favor of the denitrification reaction.