The invention discloses a dragging device, particularly a dragging device for a large and medium hydro-generator attribute test which is a power and protection device for dragging a hydro-generator to start running, raise speed, run at constant revolution speed, and slow down till stop. The dragging device comprises a power part, a jack-up part, a hydro-generator, a direct-current motor, an adjustable power supply, an universal coupling, an oil thinning station, a wheel shelf and a lifting table. The dragging device can adjust according to the running state of the generator so as to alternate the shaft friction state of the hydro-generator from sliding friction to rolling friction. The dragging device is applied to dragging the large and medium hydro-generator to a rated revolution and then testing the no-load characteristic, the short circuit characteristic and the bearing temperature of the hydro-generator. By using the invention, when starting, the resisting moment of the hydro-generator motor, the starting torsion of the direct-current motor, the output power, the electric energy loss, the starting current and the power grid voltage fluctuation are all small. When the hydro-generator runs at a low speed, the device can protect the hydro-generator bearing bush from being burnt. The device of the invention is novel in structure and is safe and stable in running.