Evaluative it patterns, as an important device for writers to express attitudinal and evaluative meaning, have increasingly been one of the topics of Corpus Linguistics. By adopting the corpus-based approach, this paper explores the frequencies, types , and functions of the it is ADJ that subpattern in evaluative it patterns. Results show that: in terms of frequency, the use of it is ADJ that occurs significantly more frequently in native learners' texts than in Chinese learners' texts. In terms of types, there are obvious differences between the two. The types used by native learners are more diverse, while Chinese learners are more single. The function of it is ADJ that is mainly reflected in its adjective use, and the semantic preferences of the patterns of two are significantly different. Native learners make greater use of the patterns to assess likelihood of propositions whereas Chinese middle school learners use them more often to imply certainty. The results of this study shed light on the teaching of English teaching practice of this structure.