Disclosed is a device for outputting high and/or low energy X-rays, in which the electron gun power supply provides power to the electron linear accelerating tube under the control of the control system; the microwave power source accelerates electron beams generated by the electron linear accelerating tube under the control of the control system; the electron linear accelerating tube is connected to the electron gun power supply and the microwave power source respectively, to generate high energy electron beams; the high-voltage electron gun power supply provides power to the high-voltage electron gun under the control of the control system; the high-voltage electron gun is connected to the voltage electron gun power supply to generate low energy electron beams; the radiation target receives the high energy electron beams to generate high energy transmission X-rays, and/or receive the low energy electron beams to generate low energy reflection X-rays. The present invention can be applied in the radiotherapy and the medical imaging, or can be applied in the nondestructive inspection.