Abstract: In order to investigate the strengthening effect of biochar on the domestic sewage treatment capacity of constructed wetland (CW) as well as for the reuse of sludge, a vertical upflowed CW was constructed using zeolite and sludge biochar as substrates, with zeolite-based CW A as the control group, and two groups of wetlands B and C with different biochar dosages were set up with the top filler V(biochar)∶V(zeolite) as 1∶2 and 1∶1, respectively. The enhanced effect of sludge biochar and its dosing on nitrogen and phosphorus removal in CW, and the effect of hydraulic retention time (HRT) on pollutant removal were explored. The adsorption characteristics and mechanism of sludge biochar on TP were analyzed by static adsorption experiment and characterization data. The results indicate that the dosage of sludge biochar significantly improved the efficiency of pollutant removal. Compared with group A, group C had better removal effect on COD, TN, NH₄⁺-N, and TP, with removal rates increased by 7.56, 15.99, 11.97, and 40.77 percentage point, respectively. Longer HRT is more conducive to pollutant removal, when HRT=3 d, the removal rate presented better results. The adsorption kinetics of TP by sludge biochar corresponds to the quasi-second-order kinetic equation, while the adsorption isotherm is consistent with the Langmuir model. The maximum adsorption capacity of sludge biochar for TP is 1.42 mg·g^-1. The adsorption mechanism mainly included physical adsorption, functional group complexation, and mineral precipitation. The research has proved the high adsorption capacity and low cost of sludge biochar, along with its good application potential on wetland filler. It also extends its massive reference significance in terms of water pollution issues.