介词是英语学习中的难点和重点,中国学习者由于受母语的影响,很难掌握英语介词。本文就中国学习者对最常用的一个方位介词“下”的义项的认知特点,从认知角度分析了汉语介词“下”这个词的语义扩展和英语介词under语义的扩展,并进行比较,找出异同,从而使得学生更好地理解、掌握英语的介词的语义。 Prepositions are the difficulties and focuses in English learning. Because of their mother tongue, Chinese learners find it hard to master English prepositions. This paper analyzes the cognitive features of Chinese learners’ semantic meaning of the Chinese preposition “under ” and the expansion of the semantics under English prepositions, And compared to find similarities and differences, so that students better understand and master the semantics of English prepositions.