Abstract: A foldable bed which can be detachably mounted onto a crib has a foldable main frame and a foldable secondary frame pivotally connected with the main frame. The main frame is able to be detachably mounted onto the crib and the secondary frame is able to be detachably and pivotally mounted on top of the main frame. The secondary frame has a fabric mat fitted thereto, onto which a baby can be placed at a height convenient for changing of a diaper. When the folded bed in not in use, it is convenient for the user to dismount the foldable bed from the crib and fold it for storage.