There are several reasons why Obama can successfully ascend to the presidency of the United States: First, there is a good opportunity and a "window of opportunity". The current president will not be re-elected and the vice president will not run for office. At the same time, the Bush administration was summed up by most Americans as "putting the country on the wrong path" for eight years, which brought trouble to John McCain and the party. Second, the image is good. Compared with McCain, he is smarter, younger, more energetic, more energetic, more appealing, more approachable and good at listening, not to mention the legendary life experience and the concrete embodiment of the "American Dream"; Third, the timing and strategy of the election campaign are properly grasped and the running partner is selected. The opponent is not so much McCain as Hillary. The two are inextricably linked in the inner-party elections. Obama is a plastic political star, while Hillary has been famous for a long time and is determined to win. There is a clear difference between those who support her and those who oppose her. Taking change as the campaign slogan, giving voters hope and choosing Biden as the deputy not only made up for the lack of diplomatic experience, but also stabilized the concerns of many white voters. Fourth, it reflects the evolution of American society itself. The lack of gender, color and race are the main social and psychological obstacles, which is a historic progress for most voters and the United States itself.