Metal regular polyhedral prism is a high-precision standard instrument mainly used to verify the indexing error of circular indexing instruments such as optical indexing heads, indexing tables, and angle measuring instruments. It can also be used as a positioning reference for angles in high-precision mechanical processing or measurement. It is divided into even and odd surfaces, with the former having a working angle of integer degrees. It is used to verify large periodic errors in the axis system of circular indexing instruments and can also be used for diameter measurement; The working angle of the latter is non integer degrees, which can comprehensively verify the large period error of the axis system of the circular indexing instrument and the small period error of the micrometer, and can correctly determine the uncertainty of the circular indexing instrument.