Poor readability in concordance result makes the prompt application of corpus in language teaching difficult. This article proposes an adaptive approach to improve concordance readability. The approach, based on the observation that readability is relevant to both text and individual reader, incorporates into the concordance process two types of information: sentence Dale-chall Index and user?s reading ability. The Dale-chall Index for each sentence in the corpus is computed with an adapted Dale-chall Index computation algorithm. The user?s reading ability is measured by an adaptive reading assessment which is built within the framework of Item Response Theory. Initial test shows that the concordance readability is improved to a large extent.