Abstract: Improving the provision efficiency of transport facilities and public services to strengthen the support for the agglomeration of population and economic activities is crucial for the sustainable growth of cities. This paper constructs a theoretical model based on the New Economic Geography framework to explore the synergistic mechanism of provision efficiency of transport infrastructure and city size affecting urban productivity. We employ prefecture and higher city level panel data from 2004 to 2016 to do the empirical analysis. The results indicate that the marginal productivity gained as city grows in size will increase with the improvement of the provision efficiency of transport infrastructure and public services. For average-sized cities, every 0.1% increase in the provision efficiency will lead to a 0.13% increase in urban labor productivity. The estimation results remain tenable after endogeneity is taken into consideration and robustness test is conducted. The empirical estimation results of the sub-region suggest that, the agglomeration benefit released by provision efficien- cy improvement is larger in eastern regions than in central and western regions. Large cities can benefit more from the improvement of provision efficiency.

Key words: transport infrastructure, provision efficiency, city size, urban productivity