The invention relates to a cylindrical-turnplate permanent magnet speed controller, which comprises a first shaft and a second shaft; the first shaft is provided with a common-bottom double-cylinder steel turnplate, and an inner conductor cylinder and an outer conductor cylinder which are opposite to each other are arranged in an inner cylinder and an outer cylinder; the second shaft is provided with an additional shaft, a bushing and a permanent magnet turnplate, the bushing is connected with the additional shaft through splines, the permanent magnet turnplate is a single cylinder, and is made of nonferromagnetic material, the cylinder is provided with a circle of permanent magnets, the polar directions of which are perpendicular to the axial line of the turnplate, neighboring magnets are heterospolarly mounted, and the cylinder is arranged between the inner and the outer conductor cylinders; and an adjusting mechanism which comprises an inner round sleeve and an outer round sleeve is arranged outside the additional shaft and the bushing. Since the speed controller adopts cylindrical coupling to replace planar coupling, axial force does not exist, the coupled surface is large, moreover, the permanent magnet turnplate can axially move, the effective engaged parts of the permanent magnet turnplate and the conductor cylinders are changed, so that the torque transferred between the permanent magnet turnplate and the conductor cylinders can be changed, consequently, repeatable, regulatable and controllable output torque and rotation speed can be obtained, and energy can be saved in the process of speed regulation.