To investigate the effect of plant presence on the carbon dioxide flux, we established nine constructed wetlands using two plant species. Results showed that carbon dioxide emissions have no difference between constructed wetlands with and without plants, 88.90 mg CO2 m-2 h-1 and 34.73 mg CO2 m-2 h-1 respectively (P > 0.05), in accordance with microbial biomass carbon and total organic carbon content (P > 0.05). The carbon dioxide emissions in constructed wetlands planted with Phragmites australis and Lythrum salicaria had no significant differences (P > 0.05), but they were significantly higher than in constructed wetlands without plant (P < 0.001). Similar with carbon dioxide emissions, the total organic carbon concentration and microbial biomass carbon in constructed wetlands with and without plant was not significant differences (P > 0.05). The total organic carbon concentration in constructed wetlands planted with Phragmites australis and Lythrum salicaria had no significant differences (P > 0.05). Hence, plant presence and plant species are important factors in regulating plant aboveground biomass and total organic carbon removal but not affect carbon dioxide emission in constructed wetlands.