The utility model relates to a mechanical type attenuator for nuclear power, establish damping system's box in mainly including, fixing device is connected to box one end, the stroke casing is connected to the other end, be equipped with the stroke rack that to control the attenuator stroke in the damping box, and the synchronous gear who meshes with it, the fixing device inner chamber can be goed deep into to stroke rack one end under load, the other end is connected with stroke casing II, with the coaxial speed -up gears I of arranging of synchronous gear, reach the acceleration rate effect through the meshing with the speed -up gears, stroke rack and synchronous gear right side in the box cavity, and speed -up gears I and II left sides of speed -up gears, set up and realize that external load slows down the damping actuating mechanism I and damping actuating mechanism II of effect. This mechanical type attenuator compact structure, the atress is reasonable, and the performance is steady, inhales to shake effectually, can form soft rigid support to the vibration of temporal large amplitude, has improved nuclear power equipment's security and reliability effectively.