The utility model relates to a mechanical indicating gauge of rotary speed. A counterweight block 1 is arranged on a cassette mechanism of the utility model; the counterweight block which is arranged on a supporting shaft 2 is movably matched with the supporting shaft 2 on which a gear D1 tightly assembled; a hollow shaft 4 is sheathed on the supporting shaft; a gear D2 is tightly assembled on the hollow shaft; synchronous gearsets D3, D4 are arranged on a stationary shaft 3 on the counterweight block. The utility model is characterized in that two stationary shafts 7, 8 are also arranged on the counterweight block; two sets of synchronous gears are respectively arranged on the stationary shafts 7, 8, and thus a variable-speed multi-stage gear set is formed. With the indicating gauge, a variable-speed ratio can be varied in an upper limit between 1-64 and even higher upper limit, and thus the utility model can be suitable for stepless variable-speed mechanism. The utility model has the advantage of reasonable structure.