Abstract Fe3O4 magnetic porous microspheres (MPMs) were successfully synthesized by an easy one-step solvothermal method. The structure, specific surface area, and magnetic property of the MPMs were analyzed and confirmed by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Brunauer–Emmett–Teller (BET) method, and vibrating sample magnetometry. The application of the MPMs in the treatment of Hg-containing wastewater released from a polyvinyl chloride plant by calcium carbide method was researched. Results indicated that the pore size of Fe3O4 MPMs ranged from ∼31.0 to 56.0nm, their BET surface area was 86.39m2/g, and their pore volume was 0.3528cm3/g. Their saturation magnetization was 87.15emu/g. Their adsorption efficiency for mercury reached 99.1%, and the Hg concentration in wastewater can be decreased from 24.18 to 0.242μg/L, in accordance with the national discharge standard of China. The saturated adsorbent of Fe3O4 MPMs was regained easily with a magnetic field and reused for 10 times after desorption by 0.1% HNO3. The adsorption of Hg2+ by the MPMs well fitted the Langmuir isotherm model and followed pseudo-second-order kinetics. These results can enable the rational design of MPMs for the treatment of Hg-containing wastewater.