The invention belongs to the field of cable bending devices and particularly relates to a flexible bending device for a high-voltage cable. The cable is clamped through a swing jacket in a limiting mechanism, the swing jacket can gradually swing along with bending of the cable, in the process, the swing jacket and the cable do not move relatively, friction is avoided, and thus damage to a sheath of the cable is avoided. The cable is clamped through the swing jacket, thus the cable and the bending device do not need to be grabbed and fixed by a person in the cable bending process, and using inconstruction, in particular to high-altitude stringing construction is facilitated; and construction operation is facilitated greatly, the disadvantage that the construction quality, technology and progress are influenced due to nonstandard manual bending operation is avoided, and the construction efficiency is improved.