The newly declassified archive materials of both the U.S. and Taiwan reveal the impact of the 1970 Peng Mingmin incident on the process of Sino-U.S. thaw, and shed new light on the dynamic relations of Washington-Taipei-Beijing triangle. In early 1970, Peng Mingmin as the wouldbe leader of the Taiwan Secession Movement fled Taipei and was finally allowed to enter the U.S. in September that year, despite the intense oppositions of the Kuomintang regime and Beijings furious condemnation. The incident took place in the initial phase of SinoU.S. Rapprochement and further deteriorated the knotty relationship between Washington and Taipei. Nevertheless, Pengs case, initially viewed as a hot potato by the American decision makers, finally led to the forming of a tacit alignment against the Taiwan secessionists among the three parties to consolidate the shared stance of OneChina principle at the time when there existed mutual antagonism cross the Strait.