The invention discloses a mechanical structure. The mechanical structure comprises a rotating piece A, a rotating piece B, a rotating piece C, a rotating piece D, sliding structural bodies A, sliding structural bodies B, sliding structural bodies C and sliding structural bodies D. Sliding ways A are formed in the rotating piece A, the sliding structural bodies A are matched with the sliding ways A, circular arc structural bodies A are arranged on the sliding structural bodies A, the circular arc structural bodies A and the sliding structural bodies A are arranged in a swing or rotating mode, and the circular arc structural bodies A are controlled by a rotating and stopping control body A; and circular arc structural bodies B are arranged on the sliding structural bodies B, circular arc structural bodies C are arranged on the sliding structural bodies C, circular arc structural bodies D are arranged on the sliding structural bodies D, the circular arc structural bodies A and the circular arc structural bodies B are arranged in a transmission mode through a traction transmission body AB, the circular arc structural bodies C and the circular arc structural bodies D are arranged in a transmission mode through a traction transmission body CD, and the rotating piece B and the rotating piece C are arranged in a transmission mode. The mechanical structure can serve as a transmission component and has the advantages that the structure is simple, speed adjusting is convenient, and reliability is high.