This paper is to analyse the development of the U.S.-China relationship and pending issues and implications. To this end the paper is composed of 6 chapters titled instruction; the relationship between the US and China in the early and hostile confrontation period; the relationship of US-Chinese approach/normalization period and the relationship in the 1980s and 1990s; the relationship by mid-2010 since the opening of the G2 era; the US-China relations and major pending issues and implications in the era of Trump-Xi Jinping; and conclusion. The rapid growth of China over the past three decades has changed the existing US-centered international order and has triggered competition between the two countries. The United States and China have become the only countries that regularly hold strategic and economic dialogue, and the topic has also developed into a country that discusses not only bilateral relations but also global issues. The issues of US-China cooperation and conflicts encompass global issues as well as bilateral relations issues. For example, the South China Sea, the North Korean nuclear issue and the THAAD, the economic and financial order, and the Taiwan issue. It is not a matter of another country, but a problem that directly or indirectly leads to Korea's diplomacy, security and economy. In order to prevent 'Korea passing' in the US-China relationship, we need a hedging strategy that maintains and strengthens the strong ROK-US security cooperation and harmonious promotion of ROK-China economic cooperation.