受到資訊技術發展的影響，虛擬環境下的互動、溝通儼然成為時下生活必需的產物，同時也被認為語言學習成功的一個決定性因素。本研究目的在探討文本式同步電腦媒介溝通能否具備有面對面的相互溝通同樣的功能，提供外語學習者溝通能力的練習，進一步的助推其在外語學習的成就。除此之外，本研究並探討文本式同步電腦媒介溝通如何影響外語學習成效。台北一所大學104位管理系學生參與此研究。參與者隨機分為52位「電腦媒介溝通」實驗組及52位「面對面口語對話」對照組。根據教科書的4個主題，實驗組及對照組的學生分別進行兩人一組的課後討論，為期4個月。經過英文程度及學習成果測驗，2份關於語言學習策略、電腦媒介溝通能力及態度問卷調查，本研究發現具有互動功能、較低的認知負荷量及社會存在感等特點的文本式同步電腦媒介溝通能夠提升學生的外語學習成效。閱讀成效明顯易見，而寫作成效需要較長的時間。本研究也發現語言學習策略中的認知、補償、情感策略為文本式同步電腦媒介溝通中間變項，進而影響非英語系國家學生的外語讀寫學習成效。同時，學生對於文本式同步電腦媒介溝通具有正面態度。因此，本研究之結果與建議將會對外語學習者在溝通式語言學習上提供一個新契機。 With the development of information technology, synchronous text-based computer-mediated communication (SCMC) has become a popular, promising medium of communication. However, it is seldom used in the domestic educational field in Taiwan even though SCMC can be an extra interface for learners to have best practice for communication. This study aimed to apply SCMC to the EFL instruction and examine whether SCMC served the same function as that of face-to-face interaction (F2F) to bring a positive effect to language learning. One hundred and four EFL non-English majors in a university in northern Taiwan participated in the study. The students were randomly divided into two groups: fifty-two SCMC and fifty-two F2F. According to the topics from their English textbooks, they respectively worked on dyad communication through SCMC and F2F outside the class time over four months. All the subjects took the simulated GEPT and filled out the first version of the questionnaire about language learning strategies before the experimental treatment. Right after the treatment, they took the language learning achievement test in the four skills and filled out the second version of the questionnaire. The results showed that SCMC had a positive effect on the EFL learners’ language learning outcomes presented in the four skills, especially in writing and reading. In addition, this study found that language learning strategies, induced by the medium of SCMC, partially acted as a mediator of SCMC to influence the EFL learners’ language learning outcomes. In the model of mediation, the learners’ reading performance was highly correlated to their use of compensative and affective strategies, whereas their writing outcomes were significantly correlated to the use of cognitive and compensative strategies. In light of the pedagogical and theoretical contributions, this study concluded that SCMC could be a good supplementary in EFL communicative instruction. Also, language learning strategies play a critical role in language learning, to which teachers can pay more attention when employing their instructional media.