Abstract: The Ba-construction is one of the most discussed topics in Chinese linguistics. In recent years, apart from its grammatical and semantic features, its textual function is getting more and more attention. This paper, by applying a set of measurements of topic continuity proposed by Givón (1983), tries to make clear how the topics of the Ba-construction behave in discourse. Through quantitative analysis, the following findings are made:the subject of the Ba-construction is most likely to become an important topic in discourse, whereas the object of Ba, being less active in discourse, is normally a secondary one; the object of Ba tends to be definite, and it is less likely to function as topic when it is indefinite; other nominal elements after the object in the Ba-construction are barely important as topic in discourse, although they could also function as one in some cases.