Abstract: In this paper,the CT system calibration model and the CT system reconstruction model are established.The accuracy and stability of the calibration model are analyzed,and the calibration template with higher accuracy and stability and the corresponding calibration model are designed.For the calibration problem of CT system,combined with geometric knowledge and receiving information,the equations are solved jointly.The gain coefficient,the detector cell spacing and parallel ray equations in all directions are calculated to establish an optimization model and the rotation center coordinates are obtained by the genetic algorithm.For the CT image reconstruction problem,the relationship between the attenuation coefficient and the pixel value is first deduced,and then the filter is used for back-projection reconstruction.Finally,the accuracy and stability of the calibration template are analyzed by computer forward simulation and reverse solution.Finally,a rectangular-circle template with high stability and a rectangular-oval-circle template with high precision are designed.