It has been 30 years since the establishment of diplomatic relations between China and South Korea, and South Korea is one of China’s most important trade partners in Northeast Asia. However, with the change in manufacturing competitiveness, the global value chain position of China and South Korea, and the rise of anti-globalization and trade protectionism, the trade between China and South Korea has also suffered a significant impact. This paper first used the international market share and trade specialization coefficient to make a quantitative comparison of the competitiveness of the primary industries of China and South Korea. Then it measured the trade integration index and export product similarity index of China and South Korea. It is found that: although China and South Korea have a particular competitive relationship in the main industrial fields, the differences in their respective areas of strength are significant, and the two countries show a good complementarity of resources. Therefore, China and South Korea should abandon suspicion, strengthen mutual trust, further optimize the trade structure between the two countries, make use of the framework of the regional agreement of RCEP, support China and South Korean enterprises to jointly develop the third-party market, and maintain and consolidate China-South Korea relations to promote the long-term development of economic and trade cooperation between the two countries.