The laser beam automatic control system is applied in the beam collimation of the laser fusion facility of "SG-II. It can be inferred from the optical analysis of Fourier, the image noise of the near and far-field caused by diffraction is the least when the near and far-field which are to detect the location of the laser beams are on the image-relay plane of the spatial filter. When correcting the beams automatically, the correlation of the near and far-field is also the least so that they can be adjusted independently. The image processing makes the automatic alignment realized with the computer and CCD camera. It can be shown from the error analysis and the experiment of automatic alignment of the system that the precision of the beam position is less than 1".