Abstract: Discussion and evaluation of traceability and uncertainty are introduced to determine results of copper-nickel-sulfide Re-Os reference material which was prepared under the technique guideline for national first grade standard material. The Cu-Ni sulfides reference materials were dissolved in Carius tubes and the Re, Os contents and Os isotopic compositions were measured by TRITON, MAT-262, Multi-Collector Inductively Coupled Plasma-Mass Spectrometry (MC-ICP-MS) and High-resolution Inductively Coupled Plasma-Mass Spectrometry (HR-ICP-MS). The contents of Re-Os and the isotope ratio of ¹⁸⁷Os/¹⁸⁸Os can be traced to benchmark materials and IUPAC respectively. The uncertainty of the data was calculated by using the authoritative ISOPLOT program for data processing. The total uncertainty was combined with homogeneity and stability of the reference material, the uncertainties of contents and compositions for spike solutions, weighting error and other factors.