Abstract: 【Objective】 To investigate the nitrogen and phosphorus purification effects of mesophytes in simulated tidal flow simulation wetland systems， which could provide plant configuration scheme combining ecological benefits and aesthetic value for urban landscape water body restoration， as well as reference for the engineering application of mesophytes in tidal flow wetlands. 【Method】 A simulated tidal flow constructed wetland system was established， and four treatments were set up according to different experimental materials， namely planting three mesophytes Ixora chinensis （IC）， Duranta repens ‘Variegata’ （DR）， Hibiscus rosa-sinensis （HR） and one typical aquatic plant Cyperus involucratus （CI）. The effects of different treatments on plant growth biomass， nitrogen and phosphorus contents， nitrogen and phosphorus accumulation， plant root system growth indexes， water quality indexes， and purification effects were studied， and correlation analysis between plant growth indicators and water quality parameters were also conducted. 【Result】 The order of plant growth biomass across treatments was HR treatment > DR treatment > CI treatment > IC treatment， with HR and DR treatments showing significant increases of 76.53% and 39.78% （P<0.05， the same below） compared to CI treatment respectively； the order of plant total nitrogen （TN） content was CI treatment DR treatment > HR treatment > IC treatment， and HR treatment achieved the highest TN accumulation of 24.35 g/m²， significantly higher than that of CI treatment （16.35 g/m²）. HR treatment exhibited higher total root length， root surface area， root volume， and root tip number than the other two mesophyte treatments. Compared with the effluent from CK， the pH values of the effluent from the simulated tidal flow wetland system with planted plants were significantly lower. The effluent dissolved oxygen （DO） concentrations for CI， HR， DR， and IC were 5.71， 5.32， 5.30， and 4.34 mg/L respectively； the removal efficiencies for TN and ammonia nitrogen （NH₄⁺-N） followed the order effluent from HR > effluent from CI > effluent from DR > effluent from IC > effluent from CK， and HR treatment showed better overall pollutant purification than CI treatment. Plant growth biomass was positively correlated with the removal rates of TN， NH₄⁺-N， and total phosphorus （TP）； TN and NH₄⁺-N removal rates were extremely significantly and positively correlated with growth biomass （P<0.01， the same below）， and root volume was extremely significantly and positively correlated with both TN and TP removal rates. 【Conclusion】 Mesophytes achieve nitrogen and phosphorus purification in water through uptake of pollutants， pH regulation， DO concentration elevation， and rhizosphere microenvironment optimization； among them， Hibiscus rosa-sinensis possesses both high decontamination capacity and ornamental aesthetic value， and can be used in plant configuration for urban integrated green-space systems.