1. A signal processing method for multi aperture sun sensor comprises the following steps: A. reading information of sunspots in a row from a centroid coordinate memory, and accumulating a sunspot number; B. judging the absence of sunspots in the row, by comparing the accumulated sunspot number in step A with a preset sunspot number; wherein if the two numbers are equal, the sunspots in the row are complete, and proceeding to step C; wherein if the accumulated sunspot number is less than the preset sunspot number, a sunspot in the row is absent, then proceeding to step F; C. comparing a column coordinate of the sunspots in the row one by one, finding the sunspot which has the maximum column coordinate, recording a column index and storage address for the maximum column coordinate; selecting a corresponding calibration parameter based on the row and column index, and outputting a centroid coordinate of the sunspot and calibration parameter to an attitude calculation module; D. calculating an attitude corresponding to the identified sunspots and accumulating the results; E. judging whether the identification of sunspots in the current row is finished, wherein identification is not finished, clearing the column coordinate value of the identified sunspot, adding 1 to the column index, then returning to step C, beginning to identify the next column sunspots, wherein if identification is finished, proceeding to step F; F. judging whether the identification of all row of sunspots is finished, wherein if the identification of all row of sunspots is not complete, adding 1 to the row index, then returning to step A, wherein if the identification of all row of sunspots is complete, averaging the accumulated attitude of all sunspots in step D, and outputting the final attitude.