Individualism is the very core of American culture and the main value in America.We can say that individualism hasbeen influencing all the fields of politics,economics and society,even the character of the nation.The self--reliance,Individualfreedom,equal competition which are emphasized is different from the concept of individualism in China.Individualism is a western concept, and the origin can be traced back to the period of Renaissance and the ProtestantReformation. In the period of immigration and Westward movement,Individualism was intensified.Although over self--centered canbring negative effect,from the whole historical point of view,there is no big social events which violate the stable situation,thisis because the concept of commitment has been in the heart of Americans for a long tlme.My paper here is trying to understandIndividualism systematically and deeply,from the origin to the influence,from the negative effect to the means of balancing.At thesame time,the paper aims at promoting the understanding and communication between the two cultures,and also to perfect our Englishstudy from the contrast and Chinese culture.