As a new type of imaging system, the light field camera can directly obtain 3D information from a single exposure of the image. In order to make more sufficient and effective use of the angle and position information contained in the light field data, complete more accurate scene depth calculation, and thus improve the accuracy of the 3D reconstruction of the light field camera, it is necessary to establish accurate geometric modeling and precisely calibrate its model parameters. This method starts from the thin lens model and pinhole imaging model, the main lens is modeled as the thin lens model, the micro modeling for pinhole imaging model, combined with the two-parallel-plane model of the light field camera, each extracted feature point is associated with its ray in three-dimensional space, the physical meaning of each parameter in the internal reference matrix is explained in detail, as well as the process of determining the initial value in the process of calibration. Furthermore, based on the radial lens distortion model, the tangential lens distortion model and the nonlinear optimization method based on ray reprojection error are further applied to improve the calibration method of light field camera. The experimental results show that the RMS ray reprojection error of this method is 0.332 mm. Compared with the classical Dansereau calibration method, the ray reprojection error accuracy of the proposed method is improved by 8% after nonlinear optimization. The derivation process of scene points and specific pixels analyzed in detail in this method has important research significance for the calibration of optical field cameras, which lays the foundation for establishment of optical model and the initial calibration of light field cameras.