In order to reduce the influence on the digital refocusing,the structure registration error in the light field camera is discussed. As for the camera in which the microlens array arranged in Matrix-style,the registration error sources are analyzed. The most important registration errors including coupled distance error,rotation error and inclination error are represented. And the registration limit conditions for the three situations respectively are suggested. The simulation experiments show that when the registration limit is exceeded,the reconstructed image will appear blurred,aliasing and other distortion,and the accurate refocusing range will be reduced.