Cultural imperialism exists not only between western and eastern countries,but also among developed nations,Canada is a typical case.The mass media in Canada are highly advanced and largely Canadian-owned but filled with American content.This dilemma has gravely threatened Canadas’ culture industry and national identity.This paper tries to uncover the historical,geographical,economical and cultural factors involved in the dilemma,which may prove to be helpful in other countries’fighting against the United States’ cultural hegemony.