The present paper has two big goals. The first aim is to extract word sequences which have high keyness in academic corpus and to discuss about a methodology of the extraction of academic key-sequences. The second aim is to consider discoursal functions of academic key-sequences distinguished from academic formulaic expressions which have high frequency in the corpus. For these goals, we use two kinds of corpus, one is, as a target corpus, 400,000 words academic corpus in the field of Korean linguistics and literature, the other one is, as a reference corpus, 10 million words a Sejong written corpus. We use these two corpus to extract word-sequences which have a relatively high keyness as well as absolutely high frequency. For identifying key-sequences for the corpora, the tool used is the program called KNU-Combiner produced by KNU research team. In order to calculate keyness, chi-squared test was used. The finally extracted key-sequence list tells us that academic key-words show the topic of the academic field, whereas the key-sequences represent the stylistic traits of the academic field, and that key-sequences play a role as a semantic unit in a specific genre like a word.