The invention discloses a method and device for preparing a superfine atomic force microscope metal probe. A homogeneous metal fracture end and a metal probe tip are respectively prepared, the metal fracture end is arranged at the fixed end of an electrical-mechanical sample rod, the metal probe tip is loaded on the movable end of the electrical-mechanical sample rod, and the two ends are oppositely arranged without contact. In a transmission electron microscope, the metal probe tip aligns with and is close to a fracture sample by piezoelectric ceramic drive; and a constant bias voltage is applied two ends at a critical contact point, and the preparation of the superfine atomic force microscope metal probe is realized by utilizing the electro-atomic migration effect. The preparation methodof the atomic force microscope metal probe is high in success rate, the growth direction and the length of a finished product are controllable, the diameter of the tip is less than 5nm, and the stability and the conductivity are good.