The present application discloses a CT system and a detection apparatus for the CT system. The detection apparatus includes: a high-energy detector assembly including a plurality of rows of high-energy detectors arranged along a predetermined trajectory; a low-energy detector assembly including a plurality of rows of low-energy detectors arranged at intervals along the predetermined trajectory, the low-energy detector assembly and the high-energy detector assembly being disposed in a stack; a number of rows of the low-energy detectors is smaller than a number or rows of the high-energy detectors; and each row of the low-energy detectors covers a row of high-energy detectors.