As an important part of transportation infrastructure, the opening of high-speed railways can produce a significant “space-time compression” effect, which can effectively reshape the spatial pattern of the tourism economy and accelerate the high-quality development of the tourism economy. This article closely combines the opportunity of high-speed railway construction in the northwest China and, based on the city-level panel data from 2010 to 2021, examines the impact of the opening of high-speed railways on the development of the tourism economy in the northwest China through the multi-period difference-in-differences model. The results show that the opening of high-speed railways significantly promotes the development of tourism economy in northwest China; through the robustness test, the paper confirms that the model construction is reasonable and the regression results are reliable. The opening of high-speed railways has significant heterogeneous characteristics for cities with different levels of tourism economic development. The opening of high-speed railways has a stronger impact on the tourism economic development of high-level and medium-level cities. The opening of high-speed rail has led to the improvement of accessibility (with the degree of impact being greater in cities with high-speed rail opened>the whole region>cities without high-speed rail opened) and the change of network centrality (with the degree of impact being in the order of degree centrality>closeness centrality>betweenness centrality), which in turn has a significant impact on the tourism economy in northwest China. Based on the analysis results and theoretical foundation, summarize the driving mechanism of the opening of high-speed railways on the development of the regional tourism economy and the integration paths of the two, and deepen the theoretical system and practical exploration of the integrated development of “high-speed rail+tourism”.