RNA processing and degradation are essential steps in gene expression regulation that influences many aspects of development and growth. In eukaryotes, virtually all RNAs are processed from longer precursors to generate mature RNAs. After completing their functions, these RNAs enter to the decay pathway. 3′- exoribonucleases, 5′ -exoribonucleases and endonucleases were involved in RNAs decay. In eukaryotic cells, part of 3′-exoribonucleases activity is contributed by the exosome, a complex composed of nine core subunits and several auxiliary components. The exosome has been shown to play an important role in processing and decaying of various RNA in animals, yeast and plants. In this paper, we briefly review the research advance of exosome in eukaryotes, and focus on the function mechanism of the exosome.