Abstract: After many years for leaning English, many students are puzzled by the question why they couldn't understand simple oral English, such as slang, because they don’t know slang. Slang is widely used in American society, which can reflect American reality life. American slang as a special language form is an indispensable part of American language. The emergence of American slang conforms to the demand of social development and times. By studying of the features and social functions of American slang, it helps us deeply understand American culture.
The whole paper consists of five parts. The first part is preface briefly introducing the background and purpose of the paper. The second part mainly describes the definitions of slang. The third part focuses on the features and origins of American slang. It begins with talking about the common features of slang, such as brevity, novelty, ephemera and friendliness, then it tells about the linguistic features of slang, and then analyze the social and cultural origins of the American slang, including the values orientation of American, the existence of all kinds of subculture group and the spring up of new things and new concepts. The forth part illustrates the social functions of American slang, for example, reflecting the speaker’s identity and status, strengthening the relationship of the group members and the internal cohesive force, reflecting the attitude of American people for the social reality, and satisfying people’s desire for freshness. Besides, it could make the language more vivid and more expressive. The last part is conclusion, emphasizing that the development of modern American slang is the demands of social and the times. By the studying of American slang we may know much about American culture and in turn get better understanding of slang by learning the cultural background behind them.
Key Words: Slang ； Features ；Social Functions

摘  要：许多人在学习了多年的“正统”英语后，仍然无法听懂一般简单的口语，如俚语，这是因为他们对俚语不了解。俚语在美国社会各阶层被广泛使用，能折射出美国现实生活的各个方面。美国俚语是一种特殊的语言形式，是美国语言必不可少的组成部分。不难看出现代美国俚语的出现是顺应社会发展和时代的要求。本文研究分析了美国俚语的特征和社会功能,可以帮助我们深入理解美国文化。
本文包含5章。第一章是前言，简单介绍了研究背景和目的。第二章主要描述了俚语的定义。第三章是侧重分析了美国俚语特征及其社会文化根源。文章首先概述了俚语一般特征：简洁、新颖、时间短和友善。之后论述了美国俚语的语言特点，然后分析了美国俚语的社会和文化根源，如：美国价值取向，多样的亚文化群的存在以及新事物和新观念的出现。第四部分重点介绍了美国俚语的社会作用，包括反映说话者的身份和地位，增强团体关系和内部凝聚力，反映美国人对现实社会的态度，满足人们对新鲜事物的追求以及使语言生动、有表现力。最后一部分是结论，强调美国俚语的发展是社会和时代的要求，通过研究美国俚语我们可以更好地了解美国文化；了解俚语背后的文化背景也可以帮我们更好地理解俚语。
关键词：俚语；特征；社会功能