The adsorption capacity of pristine biochar for hydroquinone solutions was limited, while modified biochar could significantly enhance adsorption performance. Modified biochar BCNP-Fe, BCHNP-Fe, and BCP-Fe were produced by mixing corn stover with the solutions of ammonium phosphate and ferrous sulfate, the solutions of diammonium hydrogen phosphate and ferrous sulfate, and the solutions of phosphoric acid and ferrous sulfate for removing hydroquinone solutions. The maximum adsorption capacities of BCNP-Fe, BCHNP-Fe, and BCP-Fe were 154.321, 203.666, and 142.045 mg/g, respectively, which were 1.09, 1.44 and 1.00 folds of BC. The adsorption kinetics and isotherm studies of the modified biochars probably involved physical and chemical adsorption. Thermodynamic studies further suggested that higher temperature was favorable for adsorption, and adsorption exhibited endothermic behavior. The adsorption mechanism of hydroquinone on BCNP-Fe, BCHNP-Fe, and BCP-Fe included the π-π interactions, electron donor-acceptor, hydrogen bonding, pore filling, hydrophilicity, and surface complexation. BCNP-Fe, BCHNP-Fe, and BCP-Fe were promising adsorbents for removing hydroquinone solutions as well as promising candidates for water treatment due to their simple preparation and high adsorption capacity.