Abstract: The technology of power adjusting is one of the key technologies of fuel rod ramp test. The design purpose of power adjusting device is to reach the request of power adjusting during the ramp test. The device consists of drive machine, neutron absorber and control system. The results of out-pile and in-pile tests show that the device is smoothly operated, the neutron absorber can be moved up and down with different speed by control system, at the same time it can be stopped during accident situation to provide the safe of reactor.