As CLIL (Content and Language Integrated Learning) has been widely implemented in bilingual education, the language which teachers use in class plays a key role in helping students learn content and language at the same time. This study aims to examine how content can be introduced through the use of language with different “Cognitive Discourse Functions” (Dalton-Puffer, 2013) to help students learn content knowledge and language effectively, including seven types of Cognitive Discourse Functions: describing, defining, explaining, evaluating, categorizing, reporting and exploring. This study aims to examine how Cognitive Discourse Functions can be achieved for better learning effects in bilingual science class through the use of language and multimodality, including pictures, songs, and videos. With a classroom-based approach, three bilingual science classes in 4th grade are observed, recorded, and analyzed. There are some data which have been collected for analysis. The preliminary study will be presented in the talk. Some examples of how Cognitive Discourse Functions can be categorized and used in bilingual science class will be included. Our preliminary findings show that “DESCRIBE” and “EXPLAIN” may be the most frequently-used cognitive discourse functions in the language use in bilingual science class, while the pictures and videos used to serve the function “EXPLAIN” is most frequently used in bilingual science class. This research hopes to provide suggestions for bilingual science teachers when and how they can use the language to help and facilitate their students’ learning. For example, what language would be most commonly used when teachers want to define in their teaching. Or when teachers are trying to evaluate, maybe there are some words or specific language to help students to instruct and comprehend.