1. An image display method in a Computed Tomography (CT) system, comprising steps of: implementing CT scanning on an inspected object, to obtain CT projection data; organizing the CT projection data according to a predetermined interval; extracting basic data from the organized CT projection data by using a fixed angle as a start angle and using 360 degrees as an interval; forming a Digital Radiography (DR) image based on the extracted basic data; reconstructing a three-dimensional image of the inspected object from the CT projection data; and displaying the DR image and the reconstructed three-dimensional image on a screen at the same time.