Abstract: Taking the Shizi River in Nanjing City as an example, six kinds of ecological purification scheme were combined by submerged ecological bed, ecological floating bed and biological contact oxidation technology. By inputting different degradation parameters to different units, the six kinds of water treatment technology combination scheme were simulated using the QUAL2K model. The best scheme is selected through the comprehensive evaluation of the simulation effects. The results show that the optimal scenario is comprised of a bio-contact oxidation system in the upstream, followed by an ecological floating bed in the middle stream and a submerged ecological bed in the downstream. Under this scenario, the reduction rates for biochemical oxygen demand (BOD), ammonia nitrogen (NH₃-N), total nitrogen (TN) and total phosphorus (TP) were 49.50%, 32.81%, 35.94% and 45.27%, respectively.