1. A method for loading a substrate, the method comprising:controlling a mechanical hand to take two halves of the substrate sequentially out of a substrate storage chuck, and placing the two halves of the substrate respectively on two layers of sucker assemblies of a substrate rotation apparatus at a first rotation position;
controlling the substrate rotation apparatus to be switched to a second rotation position;
controlling the mechanical hand to take the two halves of the substrate sequentially out of a lower layer of sucker assembly and an upper layer of sucker assembly of the substrate rotation apparatus at the second rotation position, so that the two halves of the substrate are arranged in a length direction of mechanical fingers, and joined together into an entire substrate, on the mechanical fingers; and
controlling the mechanical hand to convey the two halves of the substrate joined together into the entire substrate to a substrate machining device.