Due to the robust single- mode performance, mode- distortion- free splicing and compact coiling, chirally-coupled core (CCC) fiber, as a novel fiber, has provided a new method for the development of the next generation high peak power and high energy fiber laser system and aroused wide public interest over the recent years. In this paper, we describe the chirally-coupled core fiber structure and mode coupling theory in this fiber. Recent development and some important applications about the novel fiber are also reviewed.