The present invention disclosed a surgical staple (50) and staple pocket (57) for forming kidney-shaped staple therefor, with the staple pocket (57) being recessed inward on the tissue contacting surface of the staple anvil (58), and with M-shaped staple (50) being used, wherein the degree of projection of the middle portion of the back span (51) of the M-shaped staple (50) arranged at the inner circle or arrangd at a proximal side of a cutter slot (121) is larger than that of the back span (51) of the M-shaped staple (50) arranged at the outer circle or arranged at a distal side of the cutter slot (121), so that when the staple (50) of the same height are adapted to staple tissues to be stapled of different thickness, staple driver (68) bends the M-shaped staple (50) on the staple pocket (57) to form kidney-shaped staple (50) so as to achieve the operational effect of being able to seal the stapled tissue, to stop bleeding and to heal the tissue therearound.