A facile one-pot in-situ radical bulk polymerization strategy was developed for preparation of the superparamagnetic multiwalled carbon nanotubes-Fe3O4/polystyrene (CNT-Fe3O4/PS) tricomponent nanocomposite by the synergetic dispersion strategy via the multiwalled carbon nanotubes (CNT) immobilized Fe3O4 nanoparticles (CNT-Fe3O4) with oleic acid (OA) as surface modifier. Compared with the tricomponent nanocomposite prepared with the multiwalled carbon nanotubes and Fe3O4 nanoparticles added separately, immobilization of Fe3O4 nanoparticles on multiwalled carbon nanotubes could avoid efficiently aggregation of the Fe3O4 nanoparticles in polymer matrices. OA molecules adsorb onto the surfaces of the Fe3O4 nanoparticles immobilized on the multiwalled carbon nanotubes, improving efficiently the dispersibility of the multiwalled carbon nanotubes in styrene, which resulted in the well-dispersed CNT-Fe3O4/PS tricomponent nanocomposite.