Multiculturalism has received fierce controversy and discussion upon its proposal for its complexity in definition and in practice. This research discusses the definition of multiculturalism focusing on the comparison between the term “cultural pluralism” and “multiculturalism”, its influence on American society and its distinct characteristics, which is the claims of equality and identification between different cultures. It is argued that multiculturalism is not only a cultural ideology and a cultural war between the WASP-based mainstream culture and the cultures of the disadvantaged groups, but also a political and economic movement. The research also analyzes the practice of multiculturalism in the fields of political participation, education, race, media and the practice of multiculturalism that targets the disabled people and women. Moreover, the problems arise during the proposal and practice of multiculturalism are presented in the research. It is argued that the relationship between multiculturalism and homogeneous culture is not contradictory but united. A mature, sustainable and energetic national culture needs to seek common ground while recognizing and reserving the differences.