A CT image reconstructing method, a CT image reconstructing device and a CT system are provided for reducing motion artifacts in CT images in case of motion of an object. The CT image reconstructing method reconstructs CT images from projection data obtained by X-ray scanning, including a moving object position detecting step for detecting a position of a moving object in a CT image； a partial angle selecting step for selecting a view point and an angle range according to said position of the moving object and selecting data of partial angles in said projection data according to said view point and said angle range； a partial angle constraint step for generating partial angles constraint conditions according to the data of said partial angles； and an iterative reconstruction step for generating CT images by iterative reconstruction, thereby improving temporal resolution of CT images of moving objects and reducing motion artifacts.
