The invention relates to the technical field of machining tooling equipment, and discloses a clamping device of a perforated plate. The perforated plate is provided with a plurality of through holes, wherein the perforated plate is disposed on a working table surface, a plurality of sets of clamping devices are provided, each clamping device comprises an expanding-tightening sleeve, a pressing block and an inside hexagonal bolt, each expanding-tightening sleeve comprises two half-ring sleeves, an inner hole of each expanding-tightening sleeve is a taper hole, each pressing block is a taper block, an inner hole of the pressing block is a step hole, each expanding-tightening sleeve is disposed in a hole of the perforated plate, each pressing block is disposed in the inner hole of the corresponding expanding-tightening sleeve, an outer taper surface of each pressing block is matched with an inner tape surface of the corresponding expanding-tightening sleeve, each inside hexagonal bolt passes through the step hole of the corresponding pressing block to be fixed to a threaded hole in the working table surface, the outer tape surface of each pressing block is matched with the inner taper surface of the corresponding expanding-tightening sleeve to fix the through hole of the perforated plate, and the top portion of each inside hexagonal bolt is located under the upper surface of the perforated plate. The mounting and clamping device disclosed by the invention does not cause interference with the upper surface of the perforated plate, and cutting machining can be directly performed on the upper surface.