Abstract: This paper divides the 70 years of new China into six stages, analyses the course of the social construction and development, expounds the outstanding achievements, and summarizes the basic experience. It is pointed out that in the past 70 years since the founding of People's Republic of China, people's living standards have been greatly improved, industrialization and urbanization have been basically realized, historic changes have taken place in population structure and population quality, tremendous achievements have been made in combating poverty, and a social security system covering the whole people has basically been formed. The paper reveals that China is facing a series of new challenges and trends, that is, unprecedented changes have taken place in China's motive force, resource constraints and international situation for development; China will enter the ranks of high-income economies, but it is still facing the "middle-income trap"; profound changes have taken place in the relationship between labor supply and demand, and high-quality development depends on the formation of a new demographic dividend based on education and training. It is still difficult for most peasants to become the middle income group in general; solving the gap between the rich and the poor is a long-term task; the acceleration of aging, the improvement of the dependency ratio of the whole society has become an irreversible long-term trend.