Aim at the low dissolved oxygen concentration and nitrogen removing efficiency in constructed wetlands, the running parameters of aeration measure, influence on plants and bacteria, the dissolved oxygen concentration and purifying efficiency after aeration were studied. The results show that aeration should be run in the forepart of wetland. The best gas-flow ratio is 6. Continuous aeration is adopted. The influence of aeration on plants in wetlands is inconspicuous. The quantity of nitrifying bacteria and denitrifying bacteria are increased. Aeration improves the oxygen condition, which is under 0.6 mg/L before aeration but over 1 mg/L after aeration. The purifying efficiency of wetlands is improved, removing efficiency of organic matter increases 10%, and removing efficiency of total nitrogen is higher than 60%. So aeration has the value of research and application.