Computed laminography (CL) has a unique advantage for the inspection of flat objects. Geometric parameter calibration of the CL system is an important step in acquiring high quality reconstruction images. However, the existing calibration methods for the CL system can not solve all parameters in one calibration. A novel iterative geometric parameter calibration method based on the classical method for computed tomography (CT) is proposed, which can calibrate all geometric parameters by using a simple phantom. Firstly, the CT calibration method is applied to the CL system to determine the parameter sensitive to the CT method. Secondly, a new non-linear least square cost function according to the error between the practical system and the ideal system is presented, thus the sensitive parameter and other parameters are optimized by the iterative method. Experimental results prove that the proposed method can accurately calibrate all the geometric parameters, and the precision of the sensitive parameter as well as those affected by the sensitive parameter are all significantly improved. Meanwhile, the corrected geometric parameters are used to reconstruct the Shepp-Logan phantom and the printed circuit board phantom, and there are no geometric artifacts in the reconstructed images, which prove the validity of the proposed method.