The utility model provides a lubricating structure of a core bar in an overflow device of a one-rod maneuvering valve, belonging to the technical field of agricultural mechanical equipment and solving the problem that sliding is not smooth between a core bar and a guide hole of a plug screw in an existing one-rod maneuvering valve. The lubricating structure is characterized in that a lubricating channel is formed in the end face of one end of the rod-shaped part of the core bar along the length direction of a rod-shaped part, a fuel through hole communicated with the lubricating channel is formed in the outer cylindrical surface of the rod-shaped part of the core bar in a radial direction, the opening of the lubricating channel is positioned in the guide hole of the plug screw, and the opening of the fuel through hole is positioned outside the guide hole of the plug screw. The lubricating structure of the core bar in the overflow device of the one-rod maneuvering valve has a simple structure, and the sliding between the core bar and the guide hole of the plug screw is smooth without influencing the use effect of the one-rod maneuvering valve.