Abstract: In recent years, the rapid economic growth, advancement of urbanization, and continuous improvement of consumption levels have led to a significant increase in the generation of urban solid waste, including municipal refuse, construction debris, industrial solid waste, medical waste, and electronic waste. This surge has resulted in a range of serious issues, such as land resource depletion, environmental pollution, threats to human health, and resource wastage. In response, the government has introduced the concept of “waste-free cities” along with corresponding policies aimed at reducing the generation of urban solid waste at the source and promoting resource utilization. In this context, the sources, classification, and harmful effects of urban solid waste are systematically summarized. It provides a detailed overview of the relevant technologies for the harmless disposal, recycling, and preparation of high-value-added materials from urban solid waste. Building upon this foundation, the paper highlights various demonstration projects conducted in domestic cities, including waste classification, municipal solid waste incineration for energy generation, organic solid waste gasification and pyrolysis, and the extraction of valuable elements from electronic waste. Finally, corresponding policy recommendations are provided to address several challenges encountered in these demonstration projects, such as incomplete waste classification, mismatch between regional demand for waste-to-energy facilities, inadequate management of secondary pollution from harmful gases, low recycling rates of construction waste, lack of effective heavy metal extraction or harmless solidification technologies for electronic, medical, and industrial waste, and the underdeveloped preparation technologies for high-value-added materials.