<p>Previous literature has focused on the impact of HSR on population mobility, but research exploring the impact of HSR on residents’ diverse consumption from the cultural diversity perspective of population mobility is scarce. In this article, data on the opening of high-speed railways in 260 cities in China from 2007 to 2015 were collected and matched with data on private car sales. We use the time-varying difference-in-differences (DID) method to examine the impact of high-speed railway opening on residents’ diverse consumption (car brand diversity and colour diversity). This paper reveals that the opening of high-speed rail has a significant positive effect on residents’ consumption of automobile brand diversity and colour diversity. Cultural diversity plays a partial mediating role in the impact of high-speed rail opening on diversity consumption. The level of intercity mobility plays a moderating role in the impact of high-speed rail opening on diverse consumption. Furthermore, the robustness of the results was validated by parallel trend tests, the propensity score matching–double difference-in-differences method (PSM-DID), placebo tests, and instrumental variables. The findings of this article enrich the context of the impact of population mobility on cultural exchange and the influencing factors of diverse consumption and have theoretical and practical significance for understanding the impact of major national infrastructure construction on cultural diversity and residential consumption behaviour.</p>