Business English Teaching aims at cultivating students' ability to analyze and solve problems, improving students' comprehensive language competence and honing their business practical skills. Adhering to the principle of learning by doing and learning by teaching others, Case-Task Based Approach emphasizes students' ability of language use in authentic situation as well as their competence of taking part in social practices, which, to a large extent, corresponds to the objectives of Business English Teaching. Based on a diachronic combing of research ideas of Case-Task Based Approach, this writing analyzes the marketing course offered in School of English for International Business of Guangdong University of Foreign Studies through Case-Task Based Approach, expounds the implementation process of this approach and investigates into its strengths and weaknesses. Finally this writing will have a tentative exploration on how to improve the approach in practice so as to enhance the understanding of its application in Business English Teaching.