Abstract: A composite of polyethyleneimine/magnetite/reduced grapheme oxide (PMRGO) was designed and synthesized, and its structure and chemical composition were characterized by Fouriertransformed infrared spectroscopy (FTIR), transmission electron microscope (TEM), Raman spectroscopy and Xray photoelectron spectroscopy (XPS). The adsorption performance of Ag ions and colloid on PMRGO were studied in simulated pressurized water reactor coolant. The results show that PMRGO exhibits excellent adsorption performance on silver except boron and lithium ions in the simulated coolant, and the adsorption capacity increases with pH value from 3 to 8. With the increase of initial concentration of Ag, the adsorption rate of Ag on the PMRGO gradually increases. When the initial concentration of Ag is 5 mg/L, the adsorption capacity can reach 136 mg/g for Ag ions after oscillating 24 h, while for Ag colloid tends to be stable after 30 min, and the adsorption capacity is 169 mg/g. The adsorption isotherm is consistent with the Langmuir equation, and the adsorption kinetics can be described by the quasi-secondary kinetic equation.