The invention provides a magnetic material for efficiently detecting a circulating tumor cell and a preparation method of the magnetic material. The preparation method comprises the steps of: (1) allowing hyaluronic acid, 1-(3-dimethylamino propyl)-3-ethyl-carbodiimide hydrochloride, 1-hydroxybenzotriazole, cysteamine hydrochloride and dithiothreitol to react to prepare HA-SH, (2) grafting rhodamine onto HA-SH to prepare RhB-HA-SH, (3) allowing an Fe3O4 nanoparticle, RhB-HA-SH and H2O2 to react to prepare superparamagnetic fluorescent HA-SH, and (4) allowing superparamagnetic fluorescent HA-SH, 1-(3-dimethylamino propyl)-3-ethyl-carbodiimide hydrochloride, 1-hydroxybenzotriazole, PEG-FA and anti-EpCAM (epithelial cell adhesion molecule) to perform antibody reaction to prepare the magneticmaterial. The magnetic material is high in saturation magnetization, and good in magnetic response and biocompatibility, can achieve specific binding with the circulating tumor cell and has certain universality.