Light field imaging includes light field sampling and light field image processing. The light field camera based on the micro lens array can be divided into three kinds of light field cameras according to the distance between the micro lens array and the sensor: unfocused type(traditional type), focused Kepler type and focused Galileo type light field camera. The optical simulation software Zemax was used to simulate these three light field cameras. The whiteboard image obtained was calibrated with the micro lens center and the original light field image was rendered to obtain the spatial resolution and angular resolution of the system. The refocusing factor was used to derive the calculation formulas of the depth of field and the depth of focus. Considering the actual conditions and measuring objects comprehensively, the experimental system for the focused Galileo light field camera with b = 0.6f_m was constructed, where b is the distance between the micro lens array and the sensor, and f_m is the focal length of the microlens unit. Combinedly using the simulation system, the factors that affect the accuracy of the depth calibration method were analyzed. From the simulation results, it is concluded that the clarity of the original image, the sampling step, the refocusing step, the spatial resolution resampling multiple and the use of fitting are all relevant to the final depth calibration curve. The simulation conclusion was verified through improved experiments.