Abstract: A foldable structure for a hospital bed contains two mounts, a bed frame, and a bed plane, each mount including two rotary positioning pieces, wherein each rotary positioning piece has a hole and an arcuate groove to axially connect the each rotary positioning piece with two coupling elements of the bed frame, such that the bed frame rotates relative to the two mounts, the each rotary positioning piece has two orifices corresponding to two ends of the arcuate groove so that a spring pin of each side of the bed frame is inserted into one of the two orifices of the each rotary positioning pieces, hence the spring pin is pushed out of the one of the two orifices of the each rotary positioning pieces, a coupling element in the arcuate groove rotates smoothly relative to a coupling element in the hole, thus retracting or expanding the bed frame easily.