Are the spacetime compression effect caused by the operation of highspeed rail and the economic coordination committee in the urban agglomeration conducive to the market integration? There is no empirical evidence currently. Based on the data of 34 prefecturelevel cities in the Yangtze River Delta urban agglomeration from 2003 to 2015, this paper empirically analyzes the impact of highspeed rail operation and economic coordination committee of urban agglomeration on breaking down regional market segmentation by using Spatial Panel Dubin Model (SDM). The results show as follows: (1) The phenomenon of “beggarthyneighbor” does exist between the cities in the urban agglomeration of the Yangtze River Delta, but the high-speed rail operation and the economic coordination committee of the urban agglomeration significantly reduce the level of market segmentation in this region. (2) The spacetime compression effect caused by the operation of highspeed rail leads to market integration of urban agglomerations and its effect coverage extends from neighboring cities to a 2hour traffic circle. (3) The impact of HSR operations on market segmentation in other cities is greater than its impact on its own cities. However, economic coordination committee within urban agglomerations only affects neighboring cities and its spatial spillover effects on other areas are

relatively limited.