Abstract: A foldable tray comprises a baseplate, and a first side plate and a second side plate symmetrically arranged on the baseplate, both hingedly connected to the baseplate, and lie on the baseplate after being folded, and are height-adjustable side plates. An extension side plate that can be stretched out from the side plate is arranged at the top of the first and second side plates. The stretching height of the extension side plate is controlled by a prepositioning apparatus arranged in the first and second side plates. A side plate folding lock is arranged on the first and second side plates. The tray comprises roller shutter side plates symmetrically arranged on the baseplate and rolled in roller shutter storage apparatuses located in the baseplate, and can be pulled out under the action of external force. When the external force disappears, the roller shutter side plates can automatically retract.