The orderly development of county urbanization, as an effective driving force for the integrated development of urban and rural areas in the new era, promotes the interaction and flow of elements between urban and rural territorial system, the optimization and adjustment of industrial structures, the optimal allocation of resources and markets, and the organic integration of urban and rural territorial system. The results show that: (1) From 2000 to 2020, the county urbanization in China developed rapidly, and the regional differences in spatial and temporal dynamics were significant. The county urbanization rate in the eastern coastal, central suburbs and northern border areas was high, while it is low in southwest China, rural areas of the central region and most parts of Tibet and Xinjiang. In 2020, to the east of the Hu Huanyong Line, the northeastern region, northern Hebei, Shanxi-Shaanxi-Henan region, eastern Sichuan, and Yunnan-Guizhou region became high-value areas for urbanization rates at the county level. There are 716 counties with urbanization rates exceeding 50%, including the Pearl River Delta, the Yangtze River Delta, the Beijing-Tianjin-Hebei region, the Chengdu-Chongqing region, the middle and lower reaches of the Yangtze River, the border areas of Inner Mongolia, and the southeastern coastal areas of Jiangsu, Zhejiang and Fujian, accounting for 38.3% of the country's total. (2) The county urbanization in China is the result of the combined effects of factors such as population, economy, society, and culture. The level of economic development, natural environment conditions, infrastructure construction, geographic locations, public resource supply, professional entrepreneurial clusters, and macro policies affect the direction, scope and depth of county urbanization. It is predicted that by 2035, the urbanization rate of China will reach about 76.04%, and that of counties will be about 64.38%. In the future, we should strengthen the adjustment and optimization of county population, economy, society and spatial organizational structure. (3) There are five types of county urbanization in China, including factor agglomeration urbanization in counties around big cities, industrial agglomeration-driven urbanization in counties with specialized function, agricultural modernization-led urbanization in counties with main agricultural production areas, ecological conservation urbanization in counties with ecological function areas, and concentrated urbanization in counties with population loss. (4) County urbanization takes county and key towns as important spatial carriers for the agglomeration of urbanization elements, and forms a multi-level system of residence-industry and industry-city coordination. The rational spatial distribution of factors such as the development of industrial integration and population resources will further promote the interactive flow of urban and rural elements, the integration of urban and rural industries, the equalization of urban and rural residents, and the equalization of urban and rural infrastructure, and enhance urban-rural integration and network development.