Abstract: Chitosan composite microspheres encapsulating Fe₃O₄ nanoparticles (Fe₃O₄@CS microspheres) were prepared in one step by the electrostatic spraying, enabling simultaneous synthesis of Fe₃O₄ nanoparticles and microspheres. Additionally, Fe₃O₄@CS microspheres with particle sizes ranging from 90 to 1000 μm could be prepared on demand to meet the clinical embolization requirements of different blood vessels. SEM images showed that the microspheres were homogeneous in shape and uniform in size distribution ((94±3) μm). In vitro degradation experiments proved that the microspheres were biodegradable. Magnetic resonance imaging showed that the prepared Fe₃O₄@CS microspheres had excellent clinical imaging capabilities. Moreover, blood and cytocompatibility assessments confirmed the good biocompatibility of Fe₃O₄@CS microspheres. The drug-loaded microspheres loaded with doxorubicin hydrochloride (DOX) showed a typical drug sustained release curve, and the cumulative release rate of DOX was 28.82% within 72 h. These results demonstrate that one-step controllable preparation of self-imaging embolic agents show great potential for future applications in transcatheter arterial embolization (TACE).