Polyethyleneimine-modified magnetic bentonite(PEI/MB) was prepared by grafting polyethyleneimine(PEI) on the surface of magnetic bentonite(MB), characterized by FTIR、VSM、XRD、TGA、SEM and EDS, its adsorption performance of Pb2 and Cu2 in aqueous solution was studied. The results showed that polyethyleneimine was successfully grafted onto the surface of magnetic bentonite and effectively increased its adsorption capacity for Pb2 and Cu2 ; the initial pH of the solution has a great influence on the adsorption capacity, and as the pH increase, the adsorption capacity increase. At pH=5, the initial concentration of the solution is 300mg/L, and the actual adsorption capacity of PEI/MB for Pb2 and Cu2 is 96.21mg/g and 61.08mg/g respectively; The adsorption process is more in line with the quasi-second-order kinetic model, and the adsorption behavior is more in line with the Langmuir adsorption isotherm model,which is a spontaneous endothermic process.After 5 cycles of recycling, the adsorption capacity remaine above 60%, indicating that PEI/MB has certain reusability. Studies have shown that polyethyleneimine-modified magnetic bentonite is a potential adsorbent for the removal of heavy metals from wastewater.