The micropore array structure is fabricated by nanosecond laser on 316L stainless steel surface. The microstructured metal surface shows a great absorption enhancement with a wavelength range of 200~900 nm. The diameters and heights of the micropores depend on the single laser pulse energy and laser pulse number. With the increase of the laser pulse number, the depth/diameter ratio of the micropore increases, and the ratio tends to be stable when the pulse number is more than 1200. With the same pulse number, the weaker the single pulse energy is, the larger the depth/diameter ratio is. The optical absorption properties of the microstructures are estimated by the surface light reflectivity test. For the same ratio of the micropore projected area to the total area and the same pulse number, the lower the single pulse energy is, the stronger the light trapping ability of the micropore array structure is. The formation mechanisms of the micropores and the roles of these micropores in changing metal-surface optical absorption are preliminarily discussed.