Abstract: In order to study the effects of wetland vegetation on pollutant removal efficiencies and substrate microorganism status, simulated sequencing batch constructed wetlands were vegetated with five types of plants: Acorus calamus, Typha orientalis, Lythrum salicaria Linn, Phragmites australis and Spathiphyllum wallisii. The removal efficiencies of TP, NH₄⁺-N, COD_Cr and the amount of substrate microorganisms were studied under three different hydraulic retention times (HRT): 1, 3 and 5 d. The results showed that the pollutant removal rates increased gradually with the extent of HRT. The highest TP, NH₄⁺-N and COD_Cr removal efficiencies were 90.4%, 61.7% and 96.4%, obtained at a HRT of 5 d. In comparison with other systems, the Acorus calamus system had the highest pollutant removal efficiencies under all HRTs. No significant differences of the microorganism abundance were observed among different vegetations. High correlation was shown between substrate nitrite bacteria and the NH₄⁺-N removal in all systems.