A CT detection method is provided, comprising the steps of: (1) scanning circumferentially an object to be detected by means of X-ray according to a preset angle sampling value, which represents the number of sampling points in one circle, so as to obtain a group of projection sampling data in different projection angles, the preset angle sampling value being greater than 1000; (2) processing the projection sampling data so as to obtain projection data of a plurality of virtual sub-focuses equivalent to a large focus of radiation source in a CT system; and (3) implementing an image reconstruction according to the projection data of the plurality of virtual sub-focuses.