The current study is aiming to expose the efficiency of surface flow constructed wetland (CW) assisted by Pistia stratiote and Salvinia molesta in the remediation of landfill leachates. A laboratory-scale surface flow constructed wetland was constructed to imitate the characteristic of a natural pond. Composite sample of leachates was collected and transported to the laboratory for further analysis and studies. The removal efficiency of phenol, pesticides, sulphate, chloride, colour, turbidity, total suspend solid (TSS), total dissolved solid (TDS), biological oxygen demand (BOD), chemical oxygen demand (COD), ammonia nitrate and heavy metals (Pb, Cr, Cu, Cd, Ni, Hg)). The removal of heavy metal ions in the CW was determined by using a phyto-system dynamic (phyto-SDA) model while the composite design (CCD) type of response surface methodology (RSM) was employed in this study for the optimization of pesticides and phenol removal from the landfill leachates by the constructed wetland (CW). The study also predicts that the deviation from the linearity between the heavy metals in the leachates and heavy metals in the sediment and in the plant tissues is influenced by the physicochemical status of the leachate and the mixed cultivation of Pistia stratiote and Salvinia molesta. The study reaffirms the role of sediments in the determination of the fate of heavy metals due to its crucial role in the bioavailability of heavy metals for uptake by P. stratiotes and S. molesta in a CW. The study also shows a positive effect of concentration and exposure time on the reduction efficiency of both pesticides and phenol. The result shows that exposure time and concentration of phenol and pesticides are useful in the optimization of the removal efficiency of pesticides and phenol.