The main role of the pinhole mask of point diffraction interferometer is to produce a nearly ideal spherical wave for interferometry through diffraction. The quality of the reference wavefront depends on the pinhole diameter, roundness and three-dimensional surface profile. The structure and principle of pinholes are introduced, and the classification and comparison of the pinhole diffraction electromagnetic field simulation technology are made. The pinhole mask processing technologies are summarized, and the machining mechanism, precision and technical features of focused-ion-beam etching and electron-beam lithography are expounded. The influence of mask alignment accuracy on measurement repeatability is pointed out. The different testing approaches and the main technical problems are analyzed and the trend of the pinhole three-dimensional topographical measurement technology is described.