The invention discloses a safety arc-extinguishing knife switch, comprising a moving contact, a fixed contact and a slide groove; the moving contact is arranged in a manner of being rotatable to the other end to contact the fixed contact, the fixed contact is of indented middle U-shaped structure, the part of the moving contact with the fixed contact is provided with a smooth protrusion portion, the protrusion portion matches with the lower portion of the fixed contact, a metal layer greater than the fixed contact in thermal expansion coefficient is attached to the outer surface of the bottom of the fixed contact, the slide groove is arranged in the outer side of the fixed contact horizontally along the length of a base, a magnet capable of moving along the slide groove is arranged in the slide groove, a link is hinged to the magnet, and the other end of the link is hinged to the lateral side of the moving contact. Various principles are used herein to extinguish arc, safety of use of electrical appliances is improved, and the safety arc-extinguishing knife switch is simple in structure, can be powered without other energy sources, and is clean and environmentally friendly.