The invention relates to an improved double-energy CT imaging method and apparatus, and belongs to the field of CT imaging. The apparatus scans a scanning object, the left half portion of a single-layer detector acquires low-energy projection data, the right half portion of the single-layer detector acquires high-energy projection data, according to a conjugation projection principle, equivalent low-energy projection data of the right half portion is obtained through the low-energy projection data of the left half portion of the single-layer detector, the equivalent high-energy projection data of the left half portion is obtained through the high-energy projection data of the right half portion of the single-layer detector, and then data processing and image reconstruction are carried out. The apparatus comprises a radiation source, a radiation source controller, a rotation mechanism, a motion controller, the single-layer detector, a metal filter, a data acquisition controller and a maser control computer. The left half portion of the single-layer detector comprises a low-energy detection element, and the right half portion comprises a high-energy detection element. The method and apparatus provided by the invention decrease the detector cost by nearly 50%.