The present invention discloses a foldable bed. A first side rail and a second side rail have an end detachably connected to a headboard and an opposite end detachably connected to a footboard. A bed slat support is arranged between the first side rail and the second side rail. The headboard includes a receiving compartment formed therein. The first side rail and the second side rail each include at least two side rail units and the side rail units are connected to each other by a couple. In dismantling, the side rail units, the footboard, the bed slats, and the bed slat support are receivable and positioned in the receiving compartment. The present invention saves transportation space, reduces transportation cost, and provides a better way of weight carrying.