By studying the relationship between urban development performance and city scale and regional difference, this paper aims at revealing the real challenges faced by small and medium-sized cities(referred to as SMSC hereafter) in China. It analyzes the growth of different-sized cities, their positions in China's overall urban system, the influence of city scale on their capability in migrant absorption, economic development, public service, and environmental remediation, as well as the capability difference among SMSCs. Results show that city scale is less a determinant in economic development capability and per capita ownership of public service than in economic performance, quality of public service, and environmental remediation capabilities. Besides, there are many other factors determined by regional differences instead of city scale. Therefore, in the context when SMSC plays an increasingly important role in the process of urbanization, relevant parties should avoid the "trap of scale," and re-position urbanization within the framework of sustainable development.
