Abstract: When socialism with Chinese characteristics enters a new era, the main contradiction in our society has been transformed into the contradiction between the growing needs for a better life and the unbalanced and inadequate development. Correct understanding and handling of the main social contradiction in the new era should be based on Mao Zedong's Contradiction Theory, thus it can be recognized that the main aspect of the main social contradiction in the new era is the unbalanced and inadequate development. Solving the problem of unbalanced and inadequate development that restricts people's growing needs for a better life depends on innovation-driven development strategy, which can get a rare historical opportunity from the Fourth Industrial Revolution. The purpose of the US government initiating the trade war is to curb China's innovation and development, thus making the economic and trade contradictions between China and America have a dual character. China now has the most complete industrial system in the world, and its industrial output is more than that of America, Japan and German together, which is the cornerstone of China's stable economic and social development and can not be shaken by any external shocks. The transformation of the main contradiction in the new era is a historical change of underlying importance, and when the main contradiction of the new era is resolved, China will become an advanced manufacturing country instead of just a big manufacturing country, which means the realization of the great rejuvenation of the Chinese nation.