We are at the historical intersection of the world’s major changes unseen in a century and the great rejuvenation of the Chinese nation. General Secretary Xi Jinping’s important judgment on the situation of China and the world is the basis for understanding China’s national conditions and world conditions. It is also the basis for proposing China’s grand strategy under the world’s major changes unseen in a century. The core of the recent major changes is the prominent change in the world’s economic structure. This text empirically analyzes the major changes in the world economic pattern, industrialization pattern, science and technology pattern, trade pattern, urbanization pattern, and modernization pattern. It ranges from assessing quantitative changes to qualitative changes, addressing the unprecedented convergence between the North and the South. The outbreak of the COVID-19 pandemic has undoubtedly accelerated changes in world politics as well as shifts in the overall dynamic of global governance. China itself is the biggest variable in the world’s major changes unseen in a century. It is both an independent variable and a dependent variable. The interaction between the two statuses has resulted in a major change in China and the world that has not been seen in a century. It has also become the greatest opportunity for China to achieve the second centenary goal.