Abstract: 3D CT is one of the popular fields of CT Research,3D Reconstruction algorithm is put forward by Feldcamp in 1984,which is algorithm basis of 3D cone beam CT.We put forward geometric parameter method,on basis of FDK(Feldcamp-Davis-Kress)algorithm,to reduce redundant calculation in reconstruction.With availability of CCD and flat-panel detector,hardware basis of 3D cone beam CT become mature.In this paper,we introduced two types of 3D CT system on basis of scientific CCD camera detector and flat-panel detector.At last, application of these two 3D CT systems in biomedical and industrial non-destructive filed are introduced.