As a teaching approach that combines content with language in the process of teaching,CBI has recently gained increasing attention both at home and abroad.This study begins with the definitions and theoretical foundations of CBI,explores the most popular five models and analyses the possibility of applying theme-based model in ESP courses.Also,the study specifies how Six T's Approach,the first thematic framework for theme-based instruction,is applied in the course of English for Science and Technology.Based on the teaching practice,it is found that by effective melt of content and language,CBI can fuel students' language learning motivation,and meantime lay a foundation for students' use of English in their future professional field.