As a typical representative of quality service industry, tourism economy is a new engine of regional economic growth under the background of “green transformation”. Through the “quasi natural experiment” of the opening of high-speed railway, this paper selects the panel data of 264 prefecture level cities in China from 2000 to 2019, and uses the double difference method to evaluate the impact of transportation infrastructure upgrading on the high-quality development of local tourism economy. It is found that the opening of high-speed railway has significantly driven the development of regional tourism economy. The “least-cost path spanning tree” and “railway information of the Republic of China” are used as instrumental variables to deal with endogenous problems, and the results are stable. Specifically, the opening of high-speed rail will promote the domestic tourism output value and the development of tourism cities; The eastern region has achieved more tourism output value, while the central and western regions have achieved higher tourism flow. In terms of mechanism research, the opening of high-speed rail drives the high-quality development of regional tourism economy by improving external traffic accessibility and optimizing the supply level of internal public services. The findings of this paper provide an important practical basis for the development of tourism economy driven by transportation infrastructure.