The present invention relates to the fields of radioactive material detection and X-ray radiation imaging inspection, and provides a system and method for performing radioactive material detection and X-ray radiation imaging inspection simultaneously at the same place, thereby solving the problem that the two means have to be conducted separately, as in the prior art. The integrated system of the invention comprises: an X-ray NII system for performing X-ray radiation imaging inspection on the object under examination; a radiation monitor placed adjacent to the X-ray NII system device to detect the radioactive rays emitted by the object under examination; the radiation monitor sets, within the detection energy region thereof, a lower limit of detection to distinguish the energy region of the detected X-rays emitted by the X-ray detection device from the energy region of the radioactive rays emitted by the object under examination, and detects the energy in the energy region higher than said lower limit of detection. The present invention realizes a compact integration of the two devices, and greatly saves space and time resources.