1. A face recognition method implemented on an image capturing device for taking group photos, comprising: obtaining one preview image; recognizing complete faces in the preview image; dividing the preview image into a plurality of default blocks if the number of the complete faces is more than or equal to a predetermined number; adjusting the default blocks into a plurality of adjusted blocks, the adjusted blocks comprising a number of complete face blocks and a number of non-complete face blocks, wherein each of the complete face blocks contains only one complete face while each of the non-complete face blocks does not contains any complete face, and one of the most adjacent complete face blocks contains one of the most adjacent complete face; analyzing the adjusted blocks to obtain a plurality of target blocks from the non-complete face blocks which is most adjacent to any one of the complete face blocks; and recognizing facial features in each of the target blocks and obtain a plurality of non-complete face blocks, each of which comprises any of the facial features.