The history of the 20+{th} century is full of struggles and the setup of the world has undergone great changes. These all are not accidental;they have profound economic and political causes. The frontier discourse rising in the United States in the late l9+{th} century was much favoured by the American rulers. Turner’s frontier thesis gradually became a theoretical foundation of Ainerican aggressive actions. In the 20+{th} century, the Russian Revolution and the changes following it, the victory of the Chinese revolution and the successful reform and opening since the l980s have all demonstrated the rightness of Marxist historical theories. Historical materlalism is the theoretical weapon through which we can examine the changes in the 20+{th} centurv and look into the prospects in the new century. The history of the 20 + {th } century is full of struggles and the setup of the world has undergone great changes. These all is not accidental; they have profound economic and political causes. The frontier discourse rising in the United States in the late l9 + {th } century was much favored by the American rulers. Turner’s frontierista became a theoretical foundation of Ainerican aggressive actions. In the 20 + {th } century, the Russian Revolution and the changes following it, the victory of the Chinese revolution and the successful reform and opening since the l980s have all demonstrated the rightness of Marxist historical theories. the historical materlalism is the theoretical weapon through which we can examine the changes in the 20 + {th } centurv and look into the prospects in the new century.