Abstract: The integrated system of closed circulating aquaculture and plant hydroponics was designed , according to the principle of agri2ecological engineering. It includes fish2ponds , vegetable and flower hydroponics trenches , circulating water treatment units. It is a new producing model for aquaculture2crop2water cleansing. The objectives of this study are demonstration of agri2ecological engineering project , and studying the relation of energy flow between aquaculture and plant hydroponics. The results of Qingpu of Shanghai indicate : ①The fish output of red tilapia ( Tilapia mossambica ( ♀) ?Tilapia nilotica ( ♂)) and obscure puffer ( Fugu obscurus) is 58 kg?m 3, 12.28 kg?m 3 respectively , during culturing , concentation of ammonia2N , nitrite2N is respectively < 1.5 mg?L-1and <0.8 mg?L -1, DO >5.0 mg?L-1; ②The hydroponic vegetable has good growth , and its maximal purification rates of ammonia2N , nitrite2N , nitrate2N , total2N , phosphate2P and COD are 57. 46 % , 51. 72 % , 3. 7 % , 10. 67 % , 9. 72 % and 21. 78 % respectively , average N/ P ratio of inlet and outlet is 6. 60∶1 and 6. 53∶1 respectively ; ③The biofilter removal rates of NH 4 2N , NO 2-2N and COD were 44.79 %, 20.31 %, 20.10 % respectively; ④The foam2separation and ozonic2sterilization device reduced the heterotrophic bacteria number by 93. 58 % , NH 4 2N by39.00%, NO 2-2N by 38. 10 % in water through the reacting unit , raised pH and DO in the water through the device.