Abstract: OBJECTIVE To develop the national primary purity certified reference material(CRM) of emodin which has traceability and high-accuracy quantity value by establishing accurate, reliable analytical method and evaluation of uncertainty. METHODS The CRM of emodin was developed by the joint certification including high performance liquid chromatography (HPLC) and differential scanning calorimetry(DSC) on the basis of Technical Norm of Primary Reference Material and related documents requirements. RESULTS The developed amodin purity CRM in accordance with Technical Norm of Primary Reference Material requirements had the standard value and uncertainty of (99.54±0.18)%(k=2, P=0.95). CONCLUSION The national primary purity CRM of emodin developed in this study possess a high-accuracy value and traceability characteristics which could provide necessary material base for medicines standardization and internationalization.