The present invention relates to an energetic ions energy-reducing irradiation device, mainly applied to energetic ions irradiation material experiments in a high energy ion beam irradiation environment, and especially suitable for irradiation experiments of nuclear materials, semiconductor devices and the like. The energetic ions energy-reducing irradiation device is mainly characterized in that a support chassis is provided with a motor, an output shaft at the left side of the motor is provided with a left rotation output disc which drives a left rotation disk driving shaft through a left driving belt, so as to drive a left rotation disk, and a left fixed disk is connected with a rotation disk support. The energetic ions energy-reducing irradiation device of the present invention has the advantages that uniform irradiation damages are formed from the surface of the material to a certain penetration depth, and a neutron irradiation damage experiment of a nuclear material can be simulated more quickly and accurately.