The Decision of the Third Plenary Session of the 20th Central Committee of the Communist Party of China proposed to "establish a sustainable urban renewal model". At present, many cities in China, especially megacities, have entered the stage of stock development, and urban renewal has become the main mode of urban construction and transformation. Through maintenance, reconstruction, demolition, improvement of public resources and other ways, urban space resources have been readjusted to better meet people's needs and better adapt to the reality of economic and social development. In the process of urban renewal, many new experiences have been explored, and difficulties and challenges have also been encountered. The "Reader's Letter" edition launched a series of reports on "focusing on urban renewal", summarizing the experience in urban renewal in recent years, and providing reference for building a livable, resilient, green, humanistic and smart city.