Extensive discussion has been carried out on the cohesive and coherent functions of megametaphor, but not its discourse framing function. Meanwhile, it is acknowledged that megametaphor contributes to discourse construction through both lexical metaphor and grammatical metaphor. However, little grammatical metaphor appears in Chinese language, and some types of English grammatical metaphor do not exist in Chinese language either. Therefore, taking Wu Yan's Speech at the first Conference of Specialty Provision and Teaching Steering Committee in Higher Education as an example, this paper argues that Chinese megametaphor could achieve all the three discourse functions of cohesion, coherence, and discourse framing only with lexical metaphors, which results from its distinctive traits. Lexical metaphors in Chinese could trigger deep conceptual cognition in people's mind by means of building a cognitive network which extends through the whole discourse, and construct mental space and information flow, thus achieving the same discourse functions of English megametaphor. Based on that, this paper constructs a tentative analyzing framework for Chinese megametaphor, hoping to provide a new cognitive perspective for Chinese discourse analysis.