Abstract: Data from 2001 to 2018 are selected to measure the urbanization of the Yangtze River delta urban agglomeration. And the impact of the opening of highspeed rail on urbanization is analyzed by using the primacy degree and timevarying DID model， and the influencing mechanism is tested by the mesomeric effect model. The results show that the first degree of urbanization in the Yangtze River delta accords with the law of “orderscale”. And the opening of highspeed rail has an impact on the first degree of urbanization; After the opening of highspeed railway， the spatial structure of regional urbanization changed to multicenter， showing a decreasing trend from the east to the west， with significant differences between coastal and inland cities. The opening of highspeed rail has a negative effect on the spatial structure of urbanization in urban agglomeration， especially in the third and the fourth tier cities; Mesomeric effect shows that industrial structure upgrading is beneficial to the upgrading of urbanization spatial structure， and the opening of highspeed railway mainly hinders the upgrading of urbanization spatial structure by restraining industrial structure upgrading.

Key words: highspeed railway, the Yangtze River delta urban agglomeration, spatial structure of urbanization, timevarying DID model, mesomeric effect model

摘要： 选取2001—2018年我国各城市数据多方面测度长三角城市群城镇化，运用首位度、多时点DID模型等分析高铁开通对城镇化的影响，并通过中介效应模型检验其影响机制。结果显示：长三角城镇化首位度符合“位序—规模”规律，高铁开通对城镇化首位度产生影响；高铁开通后区域城镇化空间结构向多中心转变，呈由东向西递减趋势，沿海、内陆城市差异显著。高铁开通对城市群城镇化空间结构产生负效应，在三四线城市尤为显著；中介效应检验发现产业结构升级有利于城镇化空间结构的优化升级，高铁开通主要通过抑制产业结构升级来阻碍城镇化空间结构优化升级。

关键词: 高铁, 长三角城市群, 城镇化空间结构, 多时点DID模型, 中介效应模型