The snowman-like Janus particles with strict partition were synthesized by seed swelling emulsion polymerization induced phase separation.The two side partition structures were continuously modified,and the amphiphilic snowman-like Janus particles with magnetic were prepared.One side of the particle has hydrophilic imidazole group(—Im),and the other side of the particle has a long chain of hydrophobic alkyl(—C18),which has a strong loading capacity of the oil phase for separation of oil and water.Meanwhile,the particles have paramagnetic responsiveness.The particles can stabilize at the oil-water interface and control the move of emulsified droplets under magnetic field for separation of oil and water.The particles can be recycled which is conform to the requirements of green chemistry.The method for preparing functional Janus particles is universal,and a series of Janus particles with different compositions and functions can be obtained through different modifications on both sides,which provides a new idea for the preparation of advanced functional polymer materials.