The present invention discloses a CT security inspection system for baggage. The CT security inspection system comprises a scanning passage through which a baggage enters and exits the CT security inspection system for baggage, a X-ray source provided at one side of the scanning passage, and, a gantry provided at an opposite side of the scanning passage, and on which a plurality of detector units are mounted. In each of the detector units, a vertex point of at least one detector unit is positioned in a circular arc with its center at a center of the scanning passage, and the detector units are arranged successively. All the detector crystal receiving faces of the plurality of detector units are within a scope of radiating ray beams with its center at a target of the X-ray source. In each of the detector units, a connection line between a midpoint of at least one of the detector crystal receiving faces and the target of the X-ray source is normal to the corresponding detector crystal receiving face.