【正文】 hanges the past playing ways of following certain rhythm, tone and acpany. Improvisation and personality is the main feature in this period. Its wild or soft rhythm impresses the audience greatly. After World WarⅡ, Americans lived a idle and scared life. Material spending bees their only way of living, especially the young men have no ambition and passion as the war has exhausted their energy and vigor. Accordingly, Jazz in this period is filled with decadence and indulgence. The musician Miles Davis expresses the mood best in his music In a Silent Way. Meanwhile, the sentimental rhythm in Jazz, wild and strong, can also be the best demonstration. In the 1980s1990s, with the development of American society, American musicians do not monopolize Jazz. It seems that each European country has its own style in Jazz for different cultural backgrounds. Jazz of this period is not a pure American music but a multielemental music of the whole world. In fact, this big change is just the result of the influence of pluralism in the society, and Jazz’s multielemental development is just the reflection of the multicultural development of American society and culture.I. Jazz –a Mirror of American Society and Culturein the 20th CenturyJazz has different characteristics in different periods, especially in the 20th century, and always serves as a mirror of American society and culture. In order to demonstrate the reflecting feature of Jazz, three big periods of 20th century are taken as a clue.A. Jazz in the 1920s In the 1920s, Jazz gets its firststep development, and brings elements from Africa and Europe, which are fused, together with Jazz, into a new music, an expression unique to America In this period, Jazz is a kind of pure American black music and the United States monopolizes this art. Jazz’s wild rhythms, corrupted lyrics expose the decadence and dark life of Americans, and truly reflect American society and culture.Jazz has a connection to the essence of America in a much more fundamental way. It is an expression of the African roots of American culture, the treasure of American culture, a musical medium that exemplifies the culture of the Africans whose culture came to dominate much of what is American. Actually, in many aspects America’s roots are in Africa. In fact, this is a factor for Jazz’s first transmission to America. Ralph Ellison perceptively describes the transformation of separate African and European cultures are at the hand of the slaves:“…the dancing of those slaves who, looking through the windows of a plantation manor house from the yard, imitated the steps so gravely performed by the masters within and then added to them their own special flair, burlesquing the white folks and then going on to force the steps into choreography uniquely their own. The whites, looking out at the activity in the yard, thought that they were being flattered by imitation and were amused by the incongruity of tattered blacks dancing courtly steps, while missing pletely the fact that before their eyes a European cultural form was being Americanized, undergoing a metamorphosis through the mocking activity of a people partially sprung from America.” (Townsend 78)Out of this fusion of African elements es an idea that Americans believe central to their identity, namely tolerance. Both cultures e to realize each other’s value. In the heart of Americans, diversity is their strength. Americans learn every day that other cultures and peoples may make valuable contributions to their way of life. This great fusion makes Jazz a distinctly American music. Jazz reflects two contradictory facets of American life. On the one hand the band features a soloist who is an individual at the extreme. On the other hand it is a team effort, where every musician is pletely immersed in what these groups does together, listening to each of other players and building on their contributions to create the music whole. In the same sense, American life is also a bination of teamwork and individualism, a bination of individual brilliance with the ability to work with others. In a word, Jazz, as an important part of American culture, is based on real peoples and things, and is the music from life. Through it, something more about America is known to the world.In the 1920s, Jazz gets its primary development, and this distinctly American music quickly finds its way to the whole America. Its wild rhythm, improvisational performing and changeable tone give listeners a fresh feeling, and it abandons traditional music forms and outdated performing ways to separate itself with other music. In this period, Ragtime, Dixieland as a branch of New Orleans impresses every American and the young man indulge them in it pletely. Jazz’s every note makes them crazy, and then the word “JAZZMAD” es into being in America. Its rhythm sometimes sounds like howling for escaping the tightened rope and sometimes is so grave like a weak patient. The changeable rhythm seems to expose the contradictory sides of their inner heart. Louis Armstrong, the king of Jazz, expresses the sad mood in his songs, like Lonesome Road, On the Sunny Side of the Street, Hotter than That, Snake Rag and etc. For example, in the song of Hotter than that, Louis repeats the word hotter hotter, hotter, hotter。 as a music form, Jazz connects with the real social life of Americans. In this period, America has experienced the First World War, and the domestic situation is unstable. The whole society is under the shadow of fear and disappointment. The war, especially for those who has witnessed it firsthand, is brutal and represents a profound failure of western civilization. The young people try to do everything to escape responsibilities, because after the First World War, there is a general prosperity in America, and they are tired of politics, economics, restrictions and international responsibilities. They are angry with the consequences of the war and likened