Abstract: In order to solve the problem of low ammonia nitrogen removal efficiency in traditional constructed wetland of plant floating island, an engineering bacteria strain with high ammonifying ablity was isolated from the laboratory to strengthen organic nitrogen decomposition in the system. The dynamic test of the ammonifying bacteria strain showed that the organic nitrogen decomposition reaction followed zero-level reaction, with degradation rate was 0.76 mg/(L·h) and organic nitrogen decomposition rate was 81.80%. The simulation ecosystem of plant floating island in wastewater treatment was constructed by the Cymbidium faberi Rolfe (Evergreen plant), and control test group was designed without adding the strain agent. The results showed that at 48 h, the organic nitrogen decomposition rate was up to 86.50% by adding the strain agent while it was 75.66% without them in the control test group in plant floating island, being increased by 11.16% after adding agent. Similarly, the organic nitrogen was 4.40 mg/L by adding the strain agent while it was 8.23 mg/L in the control group reduced by 3.83mg/L. At 72 h, the effluent ammonia nitrogen was 6.74 mg/L by adding the strain agent while at 72h it had not been degraded and at 144 h it was 9.86 mg/L in the control group. It was significant to strengthen organic nitrogen decomposition and removal efficiency by adding ammonifying bacteria because it supplies sufficient oxygen for the microorganisms adhering to the plant roots to nitrification, and it was more convenient for plants roots to absorb ammonia nitrogen as well. This study could provide reference for improving nitrogen removal effect in constructed wetland.