This paper attempts to study the triangular dynamics involving Russia, China and the United States during the post-Cold War period(1992-2014) with quantitative method. This essay presents in five chapters and additional two important appendixes. Chapter One gives a brief introduction of the research topic and national strength of the three states. Chapter Two combs and summarizes the previous studies, thus frames research questions to make up their deficiencies. Chapter Three focuses mainly on introduction of the method of quantitative measurement of bilateral relations. Inasmuch as a triangle consists of three bilateral “wings” or “legs”, the succeeding Chapter Four deals with Sino - Russian, Sino - Amercian and American-Russian relations respectively, and analyzes Russia-U.S. and China-U.S. relations’ negative correlation regularity. Last but not least, who gains an advantage position in this triangle? The concluding section will make a concerted effort to generalize the shifting of the triangle and explain China is taking an increasingly pivot role in the approximate “romantic triangle”. AppendixⅠis the event data assignment standard. Appendix Ⅱis the records of events, which are the sources of data.