Rotor ferromagnetic punching sheet, rotor assembly and manufacturing method thereof and liquid cooling pump

The invention relates to the technical field of electronic pumps, and provides a rotor ferromagnetic punching sheet, a rotor assembly, a liquid cooling pump and a manufacturing method of the rotor assembly for the liquid cooling pump. In the rotor ferromagnetic punching sheet, the surface of the rotor ferromagnetic punching sheet is provided with a plurality of magnetic steel grooves which are arranged at intervals and are used for placing the magnetic steels, wherein the length of each magnetic steel groove is greater than the width of each magnetic steel groove along the radial direction passing through the center of the rotor ferromagnetic punching sheet. By adopting a tangential magnetic pole structure with the magnetism gathering effect, the outer diameter of a rotor can be reduced onthe premise of keeping the same magnetic field intensity of the rotor, and the outer diameter of a stator can be correspondingly reduced, so that the material consumption, volume, weight and cost ofthe motor are further redu