In order to select suitable substrates to treat pre-treated wastewater by constructed wetland, the removal efficiencies of phosphorus of compound substrates which consisted of peat, vermiculite and gravel was investigated through the experiment of vertical np-flow simulation system. The composition of the substrates in four systems were 1:1:3, 1:1:2, 1:1:1 and all gravel, respectively. The removal efficiency of TP and PO₄^3--P in system 1-3 which were filled with compound substrates was up to 77% and 90%, apparently better than system 4(27%n and 21%).The substrates was suitable for profound purification. When the concentration o# TP in inflow was lower than 0.1 mg/L, the removal effect was very stable, it can make sure that the concentration of TP in outflow was lower than 0.02 mg/L and the removal efficiency was about 80%.When it was struck by the inflow with high a oncentratiun phosphorus, the removal efficiency would decrease. The price of peat and vermiculite was much higher than gravel, so the composition of 1:1: 3 was a reasonable choice for economy and efficiency. The phosphorus removal mechanism of compound substrates was mainly adsorption, which couldnt work effectively by itself. But it could form stable and sustainable phosphorus removal efficiency that having it work together with macrophyte in wetland.