Magnetic activated carbon based on oily sludge was prepared by one step method from the mixture of oily sludge rich in iron and eucalyptus sawdust. The magnetic activated carbon was characterized by SEM, BET, FTIR, XPS, XRD and VSM. The prepared activated carbon was used to adsorb ciprofloxacin hydrochloride (CIP) in the aqueous phase. The results show that there are more pores and collapse on the surface of the oil sludge based magnetic activated carbon after adding eucalyptus sawdust (MAC850). The specific surface area is 6.65 times that of single raw material oily sludge based activated carbon (OAC), which is 782.432 m2/g. In the batch adsorption experiments, the influence factors of CIP concentration, adsorbent dosage, contact time, solution pH value and coexisting ions on CIP adsorption were investigated. MAC850 has good anti-interference ability. In the solution pH range of 4-8, the CIP removal rate of MAC850 is above 85%. pH=5 is the most favorable for adsorption, and the adsorption capacity is 232.56 mg/g. The adsorption kinetics of CIP on MAC850 is consistent with the pseudo-second-order kinetic model, the adsorption isotherm model is consistent with the Langmuir model, and the maximum adsorption capacity reaches 302.11 mg/g, which is a single surface chemical adsorption. The adsorption process is a spontaneous endothermic process. MAC850 has good adsorption capacity and reusability, and the removal rate of CIP is 89.38% after seven cycles on the conditions of the temperature of 308 K, the initial CIP concentration of 150 mg/L, the amount of activated carbon of 0.6 g/L, the adsorption time of 420 min, and the liquid nature pH (4.6). The results of this work provide a theoretical basis for the harmlessness and reduction of oily sludge, and also provide a reference for CIP wastewater treatment. The adsorption of CIP on MAC850 is based on electrostatic interaction, hydrogen bonding and π-π interaction.