With the development of nano-reseach and nano-manufacture, the validity and traceability have been emphasized around the world. the Discussion Group 7 (DG7) for Nanometrology under the Consultative Committee for Length′s Working Group on Dimensional Metrology (CCL-WGDM) of the Bureau International des Poids et Mesures (BIPM ) has presented and organized 5 international comparisons for nano-samples (NANO1~NANO5). The comparison was dominated by Danish Fundamental Metrology (DFM). The comparison began in January 2005 and lasted for more than one year. The standard sample was transferred in 12 countries to carry out in three sequential loops. The comparison data were processed by DFM and the results were announced in July 2008. The results prove that the equipment for measuring grating pitch of NIM is accordance with the international nanometrology measurement level.