Abstract: Different people from different cultures may have different understandings of the same sentence because they know little about the target cultures. While the ultimate aim of English teaching as a foreign language is to cultivate students' competence to apply English correctly, fluently, and appropriately in cross-cultural communication. However, due to lack of knowledge of cultural differences, many college students fail to achieve this purpose during the actual communicating activities. It is necessary for us to study the cultural differences in some fields between China and Western countries. Using language in such communication, we often come across some idioms with distinctive cultural characteristics, so it is a very important and complicated thing for us to understand and use these idioms correctly. Therefore, in this paper, we will discuss the idioms reflecting the differences of Chinese and Western cultures in various levels with many lively, important, and interesting examples of idioms. This thesis is based on the relevant English and Chinese theory of idioms，and summarize a comprehensive definition of idioms and their basic characteristics. This thesis sum up the differences between English and Chinese idioms in comparison.
Key words: idioms; origins; cultural differences
摘要：不同文化背景的人对同一句话的理解有时是不同的。究其原因，是说话双方没有真正掌握对方的文化。大学英语教学的目的，是使学生在跨文化交流中可以 正确、流利与恰当的运用英语。而大学生在实际交流活动中，往往不能达到这一目的，这是因为他们对中两方文化差异不够了解。因此，完全有必要对中西文化差异进行详细的研究。语言是跨文化交际中最主要的手段。在运用语言进行跨文化交际时,由于民族文化差异,难免会遇到具有鲜明文化特色的成语和习语,而对此确切地理解并正确地加以运用,则是一个十分重要而又复杂的问题。习语是各国文化的精髓，反映各国的风俗习惯。因此，本文从最能体现中西文化差异的习语着手，论述习语在文化的各个层次上所反映的中西文化差异，并采纳大量生动有趣的例子作为论据进行适当的分析。本文以前人提出的有关英汉习语理论为基础，综合出了习语的定义与习语的基本特征。通过对比，总结出英汉习语的差异。
关键词：习语; 来源; 文化差异
