In this study, I have argued that Korean language knowledge (henceforth, KLK) instruction should be accomplished in accordance with communication activity and if and only if it were, it would be effective. One of the reasons which we teach KLK in the communication context is that the use of language is closely related to the human activity which is goal-oriented. So, KLK is ought to be served as source for man to act. It is well supported we look up examples vein from morpheme knowledge and lexis. As a principles of content setting, I have proposed four criteria：progressive procedure, authenticity, consistencyand simplicity. Progressive procedure means KLK education might start from unmarked or typical grammatical phenomena. Or, it may introduce a learner highly frequent grammatical phenomena initially. KLK education must be composed of real knowledge needed to actual communication in terms of authenticity. In the situation whensimilar phenomena are in need of being taught, as in the case of teaching word formation, simplicity principle is criterion for the most economic and rational account for them. Similarly the structure of sentence might be instructed according to argument structure for the sake of simplicity. Consistency means an account of a linguistic phenomenon should not violate the whole grammar system.