Since the concept of representative elementary volume (REV) of fractured rock masses is fundamental and significant in rock mechanics, it is worth studying by researchers. This paper critically reviews the latest research achievements in the field of REV of fractured rock masses. Three main aspects are discussed, which are research viewpoints and its relevant parameters, research approaches and quantitative methods. Firstly, from the point view of studying REV, the geometrical parameters of discontinuities and rock blocks, the mechanical and hydraulic parameters of rock masses are investigated in detail. Secondly, the applied conditions, merits and drawbacks of research approaches are briefly introduced, including statistical, analytical and numerical methods. Finally, the quantitative methods for determination of REV, i.e., intuitive judgment, error and coefficient of variation prediction, hypothesis tests, curve fitting and grey correlation analysis, are summarized. This paper provides reference and guidance for relevant studies.