Abstract: In the present work one of micro analysis techniques, synchrotron radiation X ray fluorescence (SRXRF) is used in the homogeneity test of algae IAEA 413 and lichen IAEA 338, which are initially produced reference materials for micro analytical nuclear techniques by the International Atomic Energy Agency (IAEA). The relative homogeneity factor H E of some elements in these two RMs are estimated based on the micro SRXRF analysis. The results show the algae IAEA 413 and lichen IAEA 338 are two kinds of new reference materials with good homogeneity certified with the minimum sample mass larger than 10 mg for micro analytical nuclear techniques.