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.
