The invention discloses a variable Mach number motion control device for a hypersonic-speed variable Mach number wind tunnel nozzle. The wind tunnel nozzle consists of a fixed curved panel, a rotating curved panel, and a wind tunnel nozzle air flow channel which is formed by the space formed by the enclosing of two side plates. The wind tunnel nozzle comprises an inlet, a shrinking segment, a throat channel, an extension segment, and an outlet. The inlet is connected with a heater, and the outlet is connected with a wind tunnel test cabin. The rear end of the rotating curved panel is fixed at the outlet of the wind tunnel nozzle. The variable Mach number of the wind tunnel nozzle is achieved through the rotation of the rotating curved panel around an outlet shaft. The motion control device comprises a drive system, a position monitoring system, and a supporting system, wherein the drive system, the position monitoring system and the supporting system are disposed at the shrinking segment. The drive system comprises an electric cylinder, a flange, a hinge, and a hinge seat. The flange is installed in the movement direction of the electric cylinder, and the flange is connected with the hinge. The hinge is connected with the hinge seat installed on the rotating curved panel. The position monitoring system comprises two displacement sensors, and the two displacement sensors are respectively disposed at left and right positions of the shrinking segment of the rotating curved panel. The supporting system comprises a pedestal and two door frame structures, wherein the two door frame structures are fixed on the pedestal.