The purpose of this article is to analyse two issues; the cause of the change in the U.S.`s policy toward China and Sino-U.S. relations, and the process of its strategy making. This article argues that. The “perception” of U.S. causes the its strategy toward China, as many theorists have pointed out. And there are three variables; the China`s intention and capability as a substantial threat to U.S., the national preferences which causes “perceived threat” and priority of threat, and the strategy making process. Through the case study of 9.11, despite constant mood of China rising, U.S. national preferences and interaction are determined not by threat itself, but by the “perceived threat”. Moreover, in the decision making stage, U.S. cannot adopt prudent balancing policies for reasons of domestic politics, elite/social fragmentation and other motivated biases. In the future, China`s military transparency, each regime change and mass-media for the elite/social cohesion will have affect on the strategy making process.