The high oil magnetic composite resin, which is a low crosslinking resin, was synthesized by conventional suspension copolymerization in the present work. The effect of the monomer ratio, crosslinker, initiator, modified Fe3O4, and reaction time on oil absorptivity of the resin and defined optimum reaction condition were studied. The highest oil absorptivity of the resin was about 20 g/g in chloroform and 10.5 g/g in toluene when the extent of modified Fe3O4 was 5%. Infrared (IR), X-ray diffractometer (XRD), synthetic themoanalyzer, laser particle size analyzer, and vibrating-sample magnetometer (VSM) were used to study the properties of the oil-absorbing magnetic composite resin. The magnetic composite resin can be recovered after conveniently and rapidly absorbing oil by magnetic separation techniques without excluding other mechanical techniques. (C) 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 894-900, 2004.