Abstract:It is introduced the development process of certified reference materials of total rare earth oxides contents and rare earth oxides relative contents of Baiyun Ebo rare earth concentrate. The standard value of certified reference materials is 9 elements, including REO、La2O3/REO、CeO2/REO、Pr6O11/REO、Nd2O3/REO、Sm2O3/REO、Eu2O3/REO、Gd2O3/REO、Y2O3/REO. According to the composition design, select a suitable rare earth concentrate, drying out the moisture to obtain a dry base , and by grinding (particle size < 74 μm), mechanical mixing, uniformity preliminary inspection, packaging, uniformity inspection, mathematical statistics, determine the standard value, etc, complete the development of standard samples. Ten authoritative laboratories with a high level of analytical technology were selected to determine the standard values and uncertainty of nine chemical components with accurate and reliable analysis methods. The standard sample developed of the project fills the gap of rare earth standard samples at home and abroad. The standard samples has been approved as a national standard sample by General Administration of Quality Supervision, Inspection and Quarantine of the People"s Republic of China and Standardization Administration.