A process for manufacturing a multiperforated composite part comprises the following steps: - positioning a sandblasting mask (250) on a preform (110) comprising a fibrous texture impregnated with a polymerized ceramic precursor resin, said mask comprising a plurality of openings (251) corresponding to the perforations to be made in the preform (110), - spraying abrasive particles at high speed onto the surface of the mask (250) so as to perforate the preform (110) exposed in the openings of said mask, - pyrolysis of the multiperforated perform so as to form a ceramic matrix in the multiperforated fibrous texture.