Abstract: Mott metal-insulator transition (MIT) is a fundamental concept in condensed-matter physics. The related principles have been applied to many fields, especially to the description of electron characteristics in strongly-correlated systems. Although an inherent Mott-MIT is purely electronic in origin, in practice, it is almost always accompanied by a structural transition. Such a situation complicates the understanding of the basic mechanism of Mott-MIT. It is recently reported by Zhong Fang’s group and Jiandong Guo’s group in the Institute of Physics, Chinese Academy of Sciences, Jiandi Zhang’s group in Florida International University, E. W. Plummer’s group in the University of Tennessee, and Rongying Jin’s group in Oak Ridge National Laboratory that a purely electron-driven Mott-MIT is realized on the surface of Ca1.9Sr0.2RuO4 without being accompanied by structural distortion.