The invention discloses a fluid magnetizer. The fluid magnetizer comprises a plurality of split magnetization assemblies; the plurality of split magnetization assemblies are arranged around a fluid pipeline along the circumference direction; every split magnetization assembly comprises a magnetic conduction shell and two rows of magnetic block groups arranged on the inner wall of the magnetic conduction shell; the magnetic block groups are mutually staggered and are arranged on the outer wall of the magnetic conduction shell at intervals; every row of the magnetic block groups is formed by a plurality of magnetic block groups; if the fluid magnetizer is arranged on an oil inlet pipeline, 8-18% automobile oil saving and 38-94% tail gas pollutant NO discharge are realized; and if the fluid magnetizer is arranged on a tap water inlet pipeline, the water quality is improved, the water molecule cluster structure is refined, and scale inhibition and sterilization functions are realized. The fluid magnetizer has the advantages of convenience in installation, strong magnetization effect, and novel and reasonable structure design.