The invention relates to the technical field of electromagnetic power-off brakes, in particular to an electromagnetic power-off brake for a mute rotor. Armatures comprise the upper armature and the lower armature. The end face of the upper armature and the end face of the lower armature are provided with through holes penetrating through the upper armature and the lower armature and are further movably connected via mounting bolts. In this way, an original integrated armature is made into two independent structures which are movably connected via the mounting bolts, and the rigid contact forceof the armatures with a friction disk during the power-off period is reduced; and meanwhile, a rubber ring is arranged at the connecting position of the upper armature and the lower armature, the impact between the upper armature and the lower armature as well as the rigid contact between the lower armature and the friction disk can be further buffered, and thus the purpose of reducing noise is achieved.