This article deals with the Republic of Korea(ROK)’s strategy to prepare for contingency in North Korea. What are Chinese and U.S. interests and strategies towards the Korean peninsula? What are their priorities of stabilization operation in North Korea if Kim Jong Il regime collapses? What is the ROK’s strategy to deal with the contingency and, ultimately, to achieve reunification? The main arguments in this article can be summarized into three points. First, China and the United States have different strategies toward the Korean peninsula, and it could make stabilization operation in the North inefficient and even hamper the reunification process. Second, South Korea should architect its reunification scheme in advance to provide a proper guidance and direction in implementing stabilization operation in the North and coordinating with other parties including China and the United States. Third, South Korea must consider at least three questions in designing future reunification as follows: first, which party should lead the reunification process, the United Nations or South Korea?; second, in terms of time frame, should the reunification be swift or protracted?; third, in terms of the form of reunification, should it be absorption or state-to-state reunification?