Abstract: The possible cluster structure of the proton drip-line nucleus ⁹C is of great significance for understanding the exotic structure of nuclei and nucleon interactions. Additionally, ⁹C plays a crucial role in nuclear astrophysics research. Thus great attention has been attracted by ⁹C. Researchers have conducted extensive experimental explorations on ⁹C, including studies of decay properties, energy level structure, magnetic dipole moments, nuclear astrophysics S factor, and reaction cross sections. Numerous achievements have been made, but the knowledge on ⁹C is still insufficient. This article systematically summarizes and reviews these research advancements, aiming to provide guidance for future research directions. With the construction and operation of new generations of high-intensity heavy-ion accelerator facilities, combined with new experimental methods and higher efficiency detection equipment, it is expected to obtain more precise data and deepen our understanding of the exotic structure and reaction mechanisms of ⁹C.