With the fifth and sixth census and road network data, and using a spatial interoperability evaluation model and a spatial lag model, the spatial coupling relationship between China's road transport superiority degree and urbanization rate at the county level was analyzed. The result shows that: (1) Regional difference of China's urbanization rate is significant at the county level. Urbanization rate is low in traditional agricultural areas, poor contiguous mountainous counties (districts), and the spatial mismatch between economic development and labor resources was widespread, with urbanization taking place in areas away from residents' place of origin in underdeveloped areas. (2) Regional difference of road transport superiority degree is clear between the eastern and western regions and between the transport hubs and peripheries, with a clear"pointaxis" spatial structure at the regional level. Road transport superiority degree showed a partial normal distribution at the county level. (3) The overall coverage of highways, national highways, provincial highways, and county and township roads affects road accessibility for production flow, information flow, and nonagricultural market entrance of rural production factors, which affect urbanization development at the county level. Urbanization was obviously facilitated by the presence of highway exits and railway stations. (4) The spatial interoperability grade of road transport superiority degree and urbanization rate shows a partial normal distribution, with significantly mutual influence between urbanization and road transport development levels.