The United state is playing an even more significant role in the current cross-strait relationship which affects the future security and development between Taiwan and China when its interaction grows more intimately with China. Hence, to fathom the American factors in the current cross-strait relationship is believed to be helpful to grasp the crux of the cross-strait problems. This article analyzes in stages the current relationship in strategy between the U.S and China, the interaction between Taiwan and the U.S, and the present domestic controversies in Taiwan, so as to elaborate the significance of the role played by the U.S..