There are some defects in constructed wetland, including the uneven distribution of flow, easily blocked, lack of oxygen supply systems and the unsatisfactory phosphorus adsorption capacity of the substrates, etc. The research mainly studied the function and contribution of the pool of hydrolysis acidification, the natural reoxygenation/sinking device and strengthen slot for reducing nitrogen and phosphorus. The results showed the removal efficiency of COD and SS in hydrolysis-acidification pool accounted for 38.05% and 34.82% of the total removal efficiency of system. The SS removal efficiency of the natural reoxygenation/sinking device accounted for 22.01% of the total removal efficiency of system, and the concentration of DO kept above 2.5 mg.L-1. The two strengthen slots can ensure the TP, TN, COD up to the standard of the level 1 of GB 18918-2002.