The utility model provides a device slowly falls in single speed reduction belongs to the high level instrument technical field that flees. Device slowly falls in single speed reduction is applicableto the high level and flees, including speed change mechanism. Speed change mechanism includes wiring dish, planetary reducer structure, friction pulley and is used for producing the friction portionof frictional force with the wiring dish. Planetary reducer constructs and to be fixed in the wiring dish, the friction pulley cover locate sun gear shaft that planetary reducer constructs outer and sun gear shaft simultaneous movement, the friction position is in between friction pulley and the wiring dish, the rope around locate the wiring dish just one end be fixed in the wiring dish, the otherend is connected with the mounting. Friction between this device slowly falls in single speed reduction coils through friction portion and wiring is brakied.