Recently, the China Macroeconomic Forum (CMF) seminar on hot issues was held online. This seminar focuses on the topic of "Why the next five years are the key period for the beginning of building a socialist modern country in an all-round way". Liu Yuanchun, President of Shanghai University of Finance and Economics, attended the seminar. Liu Yuanchun believed that the next five years would be a critical period for the beginning of building a socialist modern country in an all-round way, as well as a node period for key issues and core issues. He analyzed the key issues in the next five years from the perspective of leaping over the middle-income trap, breaking through the Thucydides trap, Needham problem, etc. Liu Yuanchun said that first of all, the next five years are the key years for China to overcome the middle-income trap. Last year, China's per capita GDP reached US $12551, which is close to the threshold of a high-income country of US $13000. As long as China maintains a growth rate of a few tenths of a percentage point faster than the world economy, China will be able to overcome the middle-income trap. Liu Yuanchun pointed out that although crossing the middle-income trap is a highly probable event for China, the average growth rate of about 4.7% in the past three years is still far from the 5.5% growth rate originally planned. In particular, the initial realization of socialist modernization in 2035, calculated at constant prices, means that the GDP increment and per capita GDP will double in 2035, which requires that the average economic growth rate from 2020 to 2035 should reach 4.83%, During the "Fourteenth Five Year Plan" period and the period from 2022 to 2027, the average growth rate will reach about 5.5%. However, the average GDP growth rate in the three years since the epidemic has been about 4.7%. Whether the GDP growth rate will exceed 5.5% next year deserves attention. Liu Yuanchun stressed that development economics attaches great importance to overcoming the middle-income trap because it is a sign that a country's economic system is more mature, its economic operation system is more stable, and its economic growth momentum is more normal. If the middle-income trap cannot be overcome, the benign interaction between economic development, social development and politics will not occur, and it will become a Latin American phenomenon - crisis and rise and fall alternating in the fluctuation of kinetic energy. In the next five years, whether the momentum and speed of economic growth can walk out of the bright path in the new stage of global stagflation is the biggest test for China. Liu Yuanchun said that the next five years are the key period to break through the Thucydides trap and reverse the imbalance and asymmetry of the game. He pointed out that in 2015, China's GDP reached 60% of that of the United States, and the competition between China and the United States started in an all-round way. In 2020, China's GDP will reach 70% of that of the United States, and in 2021, it will reach a record high of 76.1%. From 2015 to 2019, China's proportion in the United States' GDP will increase by an average of 1.4 percentage points every year, and in the past three years, it will increase by 4.6 percentage points every year, which is an accelerated process of catching up. If we follow the economic forecast of China and the United States this year or compare the GDP of China and the United States in the first three quarters, we will find that the proportion of China in the GDP of the United States has dropped by nearly 9 percentage points, only 68.3%. Liu Yuanchun believed that the important reason for the decline was that China's GDP growth rate fell back from 8.4% last year to about 3.2% this year, while the actual growth rate of the United States was 2%, the nominal growth rate was 9%, and the actual growth rate of China this year was about 3.2%