A method for making a reference leak includes the steps of: (a) preparing a substrate; (b) forming a patterned catalyst layer on the substrate, the patterned catalyst layer comprising one or more catalyst blocks; (c) forming one or more elongate nano-structures extending from the corresponding catalyst blocks by a chemical vapor deposition method; (d) forming a leak layer of one of a metallic material, a glass material, and a ceramic material on the substrate with the one or more elongate nano-structures partly or completely embedded therein; and (e) removing the one or more elongate nano-structures and the substrate to obtain a reference leak with one or more leak holes defined therein.