Abstract: OBJECTIVE Through establishing accurate, reliable analytical method and evaluation of uncertainty, to develop the national primary certified reference material(CRM) of cepharanthine hydrochloride. METHODS The purity of cepharanthine hydrochloride CRM was certified by the joint certification including mass balance method and differential scanning calorimetry (DSC) and the uncertainty was carefully evaluated on the basis of Technical Norm of Primary Reference Material and related documents requirements of International Standards of the International Organization for Standardization. RESULTS The purity of cepharanthine hydrochloride CRM was 99.6% and the uncertainty was 0.4% with k=2, P=0.95. CONCLUSION The national primary CRM of cepharanthine hydrochloride developed in this study has been approved and assigned as a grade primary reference material by the General Administration of Quality Supervision, Inspection, and Quarantine of the People’s Republic of China, which was numbered GBW09578. The CRM provides quality control of related pharmaceutical products with standard material and method and also provides reference for purity determination and uncertainty evaluation of other medicines and natural products.