On the basis of analysis of the victory of Obama and the Democratic Party in the 2008 election, the article explores the elections impact on American politics and society and the orientation of domestic and foreign policies of the Obama administration. The article holds that the 2008 election is a historic one in American electoral political history. The result of the election will have significant and farreaching influence on American political orientation and racial relations in American society. Centerleft will be the trend for American politics in the coming four years. Democratic control of both the White House and the Congress for the first time in the past 16 years, the high expectation and support of the public provide favorable conditions for the Obama administration to put its domestic and foreign policies into practice but the new administration still faces serious challenges.