The utility model relates to a step reinforcing and supporting structure for a middle plate of a tunnel boring machine. The equipment load of the tunnel boring machine is heavy, in order to avoid the troubles of the disassembling, the assembling and the adjusting of various pipes at the connections of a main machine and rear matched equipment, the tunnel boring machine can be integrally moved by stepping transition along a central line of a line, but only the self bearing capacity of the middle plate structure can not meet the requirement of stepping. An arc-shaped guiding table is poured at the upper part of the middle plate, so that the self-weight load of the tunnel boring machine can be spread effectively by the arc-shaped guiding table; and the reinforcing and supporting structure is arranged along the stepping direction in a full-length way, and an upturning beam is embedded in the middle plate, so that the integral strength and stability of the middle plate structure can be improved. The self-weight load of the tunnel boring machine can be transmitted to a base by the reinforcing and supporting structure, so as to protect the middle plate structure from being damaged; components in the structure system do no need to be enlarged; the reinforcing and supporting structure can be used repeatedly as a supporting component for a base pit after being disassembled, has higher economic benefit and social benefit and has a wide application value in the projects of the metro, the railway, the highway, etc.