With the development of globalization and gradual intensification of mutual dependence of the world, "hard power" which includes economic and military strength is no longer the primary consideration for many countries. They tend to pay more attention to the attractiveness of their "soft power",which includes values,life style , ideology and so forth. Just as Joseph S. Ny , the famous professor of Harvard who puts forward the concept of soft power, says ,"only by widespread communication and diffusion can a country reinforces its soft power". This is mass media's function. Since the 1990s, tens of thousands cultural products brought in from America are exported to foreign countries, including popular music, films ,TV programs, magazines, books and so forth. By making advantage of its monopoly position in media circle, the United States pursues cultural hegemonism and expands its popular culture all over the world. This thesis takes a general view of the great advantages of America multi-national media groups and how they push forward the American popular culture all over the world.
