The accuracy of binocular visual system calibration using the traditional method is poor in the depth direction. To enlarge the high-accuracy field of view (FOV) of a binocular visual system, a 3D spatial distortion model (3DSDM) based on the 3D Lagrange difference is proposed to minimize 3D space distortion. In addition, a global binocular visual model (GBVM) is proposed that contains the 3DSDM and a binocular visual system. The GBVM calibration method and 3D reconstruction method are based on the Levenberg-Marquardt method. Experiments were carried out to verify the accuracy of our proposed method by measuring the length of the calibration gauge in a 3D space. Experiments show that compared to traditional methods our method can improve the calibration accuracy of a binocular visual system. Our GBVM has a lower reprojection error, higher accuracy, and a larger working field.