The growth characteristics and purification capacity of wetland plants in different constructed wetlands was studied by simulating different wetland system with six tested wetland plants (Canna indica,Phragmites Australis,Typha angustifolia,Iris pseudacorus L.,Acorus calamus L.and Zizania caduciflora) and two substrates (sand and green sand).Results show that earthworms in the constructed wetland can promote the growth of plants.Compared with plants in sand substrate,plants in treatment of sand plus earthworm or sand plus green sand and earthworms grow better in terms of plant height,leaf length,and plant diameter,especially for plant Canna indica,Iris pseudacorus L.,and Acorus calamus L..The chlorophyll content,measured by term SPAD(Soil and Plant Analyzer Development) is also improved by earthworm.The adding of substrate(sand or green sand) combined with plant and earthworm increases the purification capacity of the simulated wetland,in terms of removal efficiency of COD,TP,NH₄-N,and TN.Sand of mall particle size is beneficial to plant growth as well as nitrogen removal,while green sand with relatively large particle size has higher capacity to remove phosphorus.