Abstract: Eight REEs in the Chinese CRMs GBW08503 (wheat powder) and GBW09101(human hair) are determined using RNAA and INAA. With an aim of eventual certification of these uncertified elements, a one step rediochemical separation procedure is used to quantitatively precipitate all the REEs. Np and Ba, two fission interference related elements, can also be quantitatively co precipitated by this one step procedure, which make the interference corrections feasible after separation. Results of present work are in good agreement with finally certified values for 4 REEs, and reasonable agreement with reference values of the other 4 REEs.