Bio-remediation of urban rivers is an important issue that has aroused extensive attention both at home and abroad. The ecological anti-seepage technology of Na-bentonite is becoming the most environment-friendly technologies. The ecological anti-seepage technology is stated and its the ecological effects is analyzed based on the principles of the eco-hydraulic engineering. The ecological effects is in a word, it is that river shapes naturalized, river channel sections diversificated, reiver bed anti-seepage naturalized, surface water and underground water connected, and interfering ecosystem minimized. It is showed that the ecological anti-seepage technology of the Na-bentonite is accord with the ecological hydraulic engineering principles perfectly and is worth making more spread rapidly.