The purpose of this study is to concretize educational method in Korean grammar teaching by analyzing on communication in a Korean grammar Class. This study is based on a clear premise：First, communication in a Korean grammar class is the critical interactional activity that actualizes grammar teaching-learning method. Second, communication in a Korean grammar class is an indicating data that displays the form and process of Grammar teaching in detail. In this premise, this study has an detailed report that 'explaining- one of the Korean grammar teaching method' by reviewing literature and analyzing experiential data. Research results may be summarized as follows； 1. The micro level：‘explaining’ is composed of [describing], [exemplifying], [knowledge framing]. 2. The macro level：The defining of teaching object differentiates the contents of ‘explaning’