The invention proposes a general adjustable round nut spanner. The general adjustable round nut spanner comprises a force application rod, a first tension rod, a second tension rod, a movable pressure rod, an extension mechanism and a stress head, wherein round holes are respectively formed in one ends of the first tension rod, the movable pressure rod and the second tension rod; locking nut tension heads are respectively fixed at the other ends of the first tension rod and the second tension rod; the extension mechanism is mounted on the movable pressure rod; the stress head is mounted at the other end of the extension mechanism for changing a distance between the movable pressure rod and the stress head; and the force application rod penetrates through the round holes in the first tension rod, the movable pressure rod and the second tension rod in sequence. The general adjustable round nut spanner can be suitable for round nuts with different sizes, solves the locking and disassembly problems of the round nuts, reduces the damage of the round nuts, and widens the application range of the round nuts.