With the signing of the treaty ANZUS among Australia, New Zealand and the United States at San Francisco on September 1st,1951, the Australia-U.S. alliance relations were formally established. The Australia-US alliance has always been regarded as the cornerstone of Australia's security and defense strategy, and plays a big role on Australian foreign policy. In recent years, as China's power grows, the U.S. begins to pay more attention to Asian affairs. Australia's strategic position to the U.S. becomes important again. On November 16, 2011,U.S. President Obama visited Australia and announced plans for a sustained new American presence on Australian soil.American troops are to be deployed to Darwin.There is a strengthening trend in Australia and U.S. alliance relations. However, as the U.S., China and Australia become more and more interdependent, the "China Factor" will always be the unavoidable question to Australia-U.S. alliance. The article elaborates on the history of the development of the Australia-U.S. alliance and analyses the future of the Australia-U.S. alliance in the context of Obama's Asian policy and China's rising. <<