Abstract: A motor-synchronous exciting brake structure having a housing containing a stator and a rotor located at the center of the stator, the two ends of the housing being respectively mounted with an end cap, and the rotor shaft of the rotor being mounted with a brake structure which is used to brake the rotor, characterized in that the brake structure is provided with a floating element slidably located at the rotor shaft and the end face of the floating element, corresponding to the end cap, is provided with a plurality of brake blocks for braking purpose, and a triggering element is slidably mounted within the floating element, an elastic element is urged by the triggering element and the floating element, and further, the end face of the triggering element, corresponding to the rotor, is formed with two corresponding guiding slots, and one side of the guiding slot is provided with a sloping face, wherein the sloping face is inclined toward the end face, the other end of the floating element is a limiting plate