Capping mechanism and freeze dryer

The utility model discloses a cover pressing mechanism and a freeze dryer, the cover pressing mechanism comprises a box body, the box body is provided with a containing cavity, a plurality of freeze-drying plate layers which are sequentially arranged from bottom to top are arranged in the containing cavity, and a movable adjusting assembly capable of adjusting the distance between every two adjacent freeze-drying plate layers and a detection piece used for detecting the levelness of the freeze-drying plate layers are arranged between every two adjacent freeze-drying plate layers; the two freeze-drying plate layers connected with the movable adjusting assembly can move up and down relatively, the freeze-drying plate layer located at the uppermost part is connected with a driving device for driving the freeze-drying plate layer to move up and down, the freeze-drying plate layer located at the lowermost part is fixedly arranged in the box body, and the two adjacent freeze-drying plate layers can be close to or s