In recent years, with the gradual implementation of the Medium and Long-term Railway Network Plan, China has entered the era of high-speed railway (HSR) network, and the impact of HSR on urban and regional spatial structure has become a hot topic of human geography research. In this study, the network structure and evolution characteristics of cities in China was analyzed from various aspects, including overall scale, network density, timing variation of node centrality, and network connection mode and strength, by using social network analysis and the ArcGIS visualization tool based on the HSR passenger flow data from 2014 to 2019. The results are presented as follows: 1) City network density has increased with the increase of HSR cities and their connections. Statistics show that 76.09% of the cities in China had been opened to high-speed trains by 2019, and each city can reach 66 cities by high-speed trains without transfer. 2) Changes in the status and functions of nodal cities have reshaped the spatial pattern of the network. The network pattern dominated by a few eastern cities in the past has changed, showing a trend of multi-center and balanced development. The core position of cities from the eastern part in the network has been further strengthened. At the same time, some cities in central and western China begin to play a more important role in the network connection, which is the link and bridgeof trans-regional connection. 3) In terms of spatial pattern, the city network expands from east to west as a whole, and an interlocking and complex network-like structure on the country scale has replaced the banded structureatthe regional scale, which is similar to the eight vertical and eight horizontal HSR network. High-speed railway has weakened the constraint of geographical distance on city connections, and the corridor effect has diminished. 4) During the construction period of HSR network, the correlation strength of city network was low, and the high-intensity city connection was scattered in several city clusters in the east, which was shown as an independent and closed regional system on the whole. With the formation and expansion of the HSR network, the original pattern of city connections has been consolidated, and continued to spread and divide, forming four distinct levels of connections.