As a way of cognitive thinking of human beings, the continuum of metonymy and metaphor and the interaction between them have been recognized by scholars. The development of digital technology and the diversity of modes of communication have brought prominence to the communicative functions of multimodal metaphtonymy. For L2 learners, multimodal metaphtonymical competence includes two aspects of multimodal communicative competence and metaphtonymical competence based on modes such as language and image, covering four dimensions: multimodal metaphtonymy identification, interpretation, evaluation and output. Similar to the cumulative construction of knowledge in semantic wave theory, the multimodal metaphtonymical competence of L2 learners is to achieve cumulative development under the continuous promotion of semantic wave. Multimodal metaphtonymical competence development model refers to three synergistic and interactive processes: identification and deconstruction, criticism and framing, conversion and construction, based on multimodal metaphtonymical discourse and second language learning environment. The integration of multimodal metaphtonymical competence development and second language learning provides a new perspective for the study of second language acquisition.