Abstract: In order to study the purifying effect of system consisted of plants and microorganisms on the intensive- aquaculture waterbody, an aquatic plants- microorganisms system in pond was established by planting Eichhornia crassipes and then adding 3.0×1010 cfu/m3 EM. Results showed that aquatic plantsmicroorganisms system had significant better purification effect on TN, NH4⁺-N, NO2^--N, TP, COD than EM (P＜0.05). After combined purification, the concentration of TN and TP decreased to the first standard of discharged water from freshwater fish pond, and the concentration of ammonia and nitrite decreased to below 0.6 mg/L and 0.1 mg/L respectively. In terms of the area of the test-groups, the purification effect of timedepend of aquatic plants-microorganisms system using was evident, and the removing rate of TN, NH4⁺-N, NO2^--N, TP was faster at first 8 days. The results also showed that the intensive-aquaculture waterbody was well purified by aquatic plants-microorganisms system established by Eichhornia crassipes and EM, and when the area of floating-bed was 20%, the ecological benefit achieved to the optimum level.