In the end of past century, with the advent of analytical instruments such as TIMS and MC-ICP-MS, the non_traditional stable isotopes, including Fe, Cu, Zn, Se, Mo, Cr, Hg, Ca, Mg etc., are developing rapidly, and have becamea very important research frontier in isotope geochemistry. Because of the special feature with the multivalences, multi-mass number and larger isotopic fractionation, Se isotopes have caused more attention. Se isotope research to date has confirmed these measurements, developed new measurement techniques, and investigated Se isotope fractionation during several other critical processes. In this paper, we summarize the chemical preparation (TCF), on-line hydride generation system,massspectrometry, scaling of standard reference materials concerning Se isotopes, and review the isotopic compositions and fractionation mechanism in natural and the experiments.