New nanocatalyst Fe3O4@MnPOM, was successfully synthesized by covalent bonding of polyoxomolybdate [PMnMo11O39]5‒ on the amino-functionalized Fe3O4@SiO2. The synthesized nanomaterials were characterized by a series of spectroscopic techniques including X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray (EDX) and infrared spectroscopy (FT–IR). The resulting nanocomposites were efficient catalyst for selective oxidation of olefins to corresponding epoxides with t–BuOOH as oxidant, in high yields and selectivity. In addition, the synthesized catalyst could be conveniently recovered from reaction mixture using applying an external magnet. The recycling tests showed that the nanocatalyst can be reused at least 7 times without significant loss of catalytic efficiency.