The invention provides a variable-speed rotary device, and belongs to the technical field of mechanical equipment. The variable-speed rotary device comprises a driving shaft, a first conical gear, a second conical gear, a spherical-surface wheel, a friction wheel, a tooth-inserted worm wheel, a worm, a driven shaft and a workbench, wherein the first conical gear is fixedly mounted on the driving shaft in a concentric manner; the tooth-inserted worm wheel can be rotatably arranged on the driving shaft; a supporting shaft is fixedly connected with the tooth-inserted worm wheel; the second conical gear and the spherical-surface wheel are mounted on the supporting shaft; the first conical gear is mutually engaged with the second conical gear; the shaft center of the regulating shaft is mutually perpendicular to that of the driving shaft; one end of the regulating shaft is provided with a handle; the worm is mounted on the regulating shaft in the concentric manner; the worm is mutually engaged with the tooth-inserted worm wheel; the friction wheel is mounted on the driven shaft; the spherical-surface wheel is mutually fitted to the friction wheel; and the workbench is mounted at one end of the driven shaft in the concentric manner. The variable-speed rotary device realizes that the rotation speed of the workbench is variable, the structure is reasonable, the cost is low and the reliability is good.