The present invention proposes a security inspection apparatus and method, relates to the technical field of radiation, wherein the security inspection apparatus of the invention comprises: 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. Such a security inspection apparatus can detect size and position information of the inspected object, and automatically adjust the position of the radiation emitting device according to the size and position of the inspected object, thereby reducing or avoiding detection dead angles, and improving accuracy of the detection.