1. A shooting parameter adjustment method for face detection, comprising: (A) acquiring an image; (B) dividing the image into a plurality of blocks, and calculating a brightness value of each of the blocks; (C) selecting a plurality of the blocks, and calculating an average value of the brightness values of the selected blocks; (D) adjusting a shooting parameter according to the average value; and (E) acquiring another image according to the shooting parameter, and performing a face detection procedure with the another image.