In this study, magnetic core-shell structure Fe3O4@MCM-41 nanoparticles were synthesized with vesicles as soft templates. in the preparation, FeCl2 and tetraethy orthosilicate (TEOS) were selected as Fe processor and Si precursor, respectively. Stable vesicles first formed in 0.03 mol.L-1 1:2 mixture of anionic surfactant sodium dodecyl sulfate and cationic surfactant cetyltrimethyl ammonium bromide. Then, TEOS was added in the vesicle aqueous solution, leading to a highly dispersed solution. After high-temperature calcination, Fe3O4@MCM-41 nanoparticles were obtained. Their structure and morphology were characterized by Saturn Digisizer, transmission electron microscope and vibrating sample magneto-meter. The results indicate that the vesicles are spherical and their size could be tuned between 20 and 50 nm. The average grain diameter of synthesize magnetic core-shell Fe3O4@MCM-41 particles is 100-150 nm and most of them are in elliptical shape. The dispersion of magnetic particles is very good and magnetization values are up to 33.44 emu.g(-1), which are superior to that of other Fe3O4 materials reported. (C) 2015 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.