1. A computed tomography (CT) image reconstruction method, comprising the steps of: Collecting all the different orientations corresponding to a projection of the data by using a center line, between central of detector and ray source, when an imaging system goes around an object every predetermined angle, and the data are recorded into geometric parameters of the imaging projection system, then the directions of the geometric parameters of the system are created as a set of three-dimensional spatial image reconstruction information; Building the imaging system of the virtual data model and simplify its three-dimensional characteristics into a simplified data model, and virtualize a set of data in a region of interest (ROI) as a forecast data, and finally input the data of the region of interest (ROI) through the simplified data model to simulate the projections; Comparing and matching the simulation projection information with the collected information on each angle of the projected image, and calculating a difference value; Processing iterative calculation of back-projection by the difference value; Correcting the original three-dimensional image reconstruction information by the difference between the values of the back-projection; Verifying the difference value whether is less than a predetermined difference value to decide to run the steps to begin or not; and Outputting the reconstructed image from all directions of the resulting simulated projection data to form a three-dimensional imaging volume.