Monkey wrench

The invention provides a monkey wrench. The monkey wrench comprises a handle (1), a cover (2), a rotating ring (3), a handle (4), a compressing plate (5), a wrench shell (6) and a fixed ring (7). The rotating ring (3) rotates under rotation of the handle (4) so as to drive the compressing plate (5) to rotate around a pin (71), so that the polygonal defined by the compressing plate (5) is changed. The mechanical seal manner is adopted, a guide rail and a working space are separated, and due to the characteristic of large supporting force of the mechanical structure, a worker can conveniently walk in the working space without barriers, and the operation requirement of the worker is met. The monkey wrench is simple in structure, capable of adapting to different nut sizes and convenient to use.