A cooling plate includes a casing being internally divided into an upper chamber and a lower chamber; an air inlet deposited on at least one lateral wall of the casing enclosing the upper chamber; a plurality of through holes being formed on the partition board and such arranged that the through holes closer to the air inlet are smaller in diameter and the through holes farther from the air inlet are larger in diameter, wherein the upper chamber and the lower chamber are communicated to each other via the through holes; and a plurality of air outlets provided on a lower board below the lower chamber for communicating the lower chamber to an exterior of the casing, wherein the air outlets are identical in diameter and arranged into a matrix-like pattern.