The plant biomass,soil CO2 and CH4 emission rates of wetland were determined and used to analyze the carbon cycling between the atmosphere,plants and soil of three wetland plants ecosystems in Dongting Lake.The results showed that the air traffic flow vegetation carbon of herbs,trees and aquatic plant systems was 6.02，6.00 and 2.01 t/(hm2·a).The plant layer carbon flux to the soil was 2.21，1.04 and 0.73 t/(hm2·a).The soil carbon flux to the atmosphere was 2.36，2.14 and 1.29 t/(hm2·a).There was carbon sink function in the carbon cycle in the atmospheric,vegetation and soil subsystem of three kinds vegetation ecosystem,which the net system productivity was in the order of the herbs (5.87 t/(hm2·a))>tree plant (4.90 t/(hm2·a))>aquatic systems (1.45 t/(hm2·a)).The content of this study only involved with the carbon cycle of wetland vegetation systems atmosphere,plants,soil between and did not involve with wetland hydrological geochemical processes in the carbon cycle.The comprehensive analysis of effects of the carbon cycle wetland system of the entire process,wetlands hydrogeochemical process on wetland carbon cycle should be the focus of further studies.