The present disclosure proposes a security inspection apparatus and method, relates to the technical field of radiation, wherein the security inspection apparatus of the disclosure includes: radiation emitting device, back-scatter detector, size-distance detecting device, orientation adjusting device; the back-scatter detector located between the radiation emitting device and an inspected object; the size-distance detecting device located between the radiation emitting device and the inspected object, for detecting a size of the inspected object and/or a distance between the inspected object and the size-distance detecting device; and the orientation adjusting device adjusts orientation of the radiation emitting device according to the size of the inspected object and/or the distance from the inspected object.