The topological Kondo insulator (TKI) is an intrinsic electronic correlated topological system in which the bulk bandgap is originated from the Kondo correlation. Since the theoretical idea of TKI was proposed in 2010, SmB₆ was predicted to be the first candidate topological Kondo insulator. In the last decade, SmB₆ was investigated extensively by various experimental methods, and the accumulated evidence confirmed that SmB₆ is a topological Kondo insulator. This review article presented some key experimental evidence, including electronic transportation measurements, ARPES study of low-energy band structure, and STM characterization of the surface. We also discussed how these experimental results establish the topological narrative of SmB₆. Meanwhile, some extremely exotic properties like the 3D quantum oscillations and the bulk-surface valence seperation of SmB₆ are exhibited. The related physical origin is still unknown and needs extra efforts to unveil the underlying physics.