This paper takes the cities in the Yangtze River Delta as an example area, uses Floyd - Warshall method to calculate the time distance between cities, and thus revises the classic economic connection indicators. Based on this, we study the spatiotemporal convergence in regional high-speed railway networks and its impact on economic ties between cities during the period from 2009 to 2019. The results confirm that the Yangtze River Delta region exhibited a strong spatiotemporal convergence during the sample period. At the same time, in the vertical dimension, the total economic connection and accessibility values of the cities showed a trend of increasing economic connection in the Yangtze River Delta city group; from a horizontal perspective, the effect of space-time compression on cities that opened high-speed rail earlier has a more significant impact on their economic ties.