Purpose To synthesize the anti-mouse matrix metalloproteinase-9 immunomagnetic nanoparticles chemically. Then to investigate the possibility of Ab-SPIO specific probe as a marker of atherosclerotic plaques detected with 7.0T magnetic resonance imaging system in mice model.Method Superparamagnetic iron oxide(SPIO) was prepared by chemical coprecipitation and coated with meso-2,3-dimercaptosuccinic acid (HOOCCH(SH)-CH(SH)-COOH) or DMSA]. The anti-mouse matrix metalloproteinase-9 immunomagnetic nanoparticles(Ab-SPIO) are synthesized by grafting anti-mouse matrix metalloproteinase-9 antibodies on the surface of DMSA-coated using the linker of EDC(1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride).The conjugation amount of the antibodies and the activity of Ab-SPIO were evaluated by enzyme linked immunosorbent assay(ELISA). Model of atherosclerosis were established by ligating the ApoE-/- mice left carotid artery and feeding with high lipid diet. The mice models were injected Ab-SPIO through tail vein. The MR imaging was performed at 0、4、6、24、48hours after the injection. Result The optical density(OD) from ELISA goes up with increasing the quality of antibodies.The samples were also measured by ELISA menthod after 3 days and 100 days respectively,and 100、200μg samples’ OD descent after 3 days.All the results above are investigated statistically.At 6 hours after the injection of Ab-SPIO into the mice models, the injured vessels showed signal intensity loss on T2WI most obviously.Conclusion The anti-mouse matrix metalloproteinase-9 immunomagnetic nanoparticles(Ab-SPIO) can be chemically synthesized by EDC, and the conjugation activity and stability still remain. It is possible to use Ab-SPIO specific particles as a marker of atherosclerotic plaques detected with 7.0T magnetic resonance imaging system in mice carotid atery.