Abstract: Based on the balanced panel data of 271 prefecture level cities in China from 2006 to 2017, this paper uses the data envelopment analysis method to measure the efficiency of urban green development, and then uses the difference in difference model and the intermediary effect model to test the impact and mechanism of high-speed rail on urban green development efficiency. The results show that:(1) on the whole, the opening of high-speed rail has significantly improved the efficiency of urban green development. This conclusion is still valid after alleviating endogenous problems and carrying out a number of robustness tests. From the perspective of dynamic effect, the pull of high-speed rail to urban green development efficiency is increasing year by year. (2) The mechanism analysis shows that the opening of high-speed rail improves the efficiency of urban green development by means of innovation effect, structural effect and configuration effect, among which innovation effect plays the strongest role, while structural effect has a weak impact. (3) The heterogeneity study found that the pull effect of high-speed rail on urban green development efficiency is more significant in the eastern region and large and medium-sized cities. (4) Based on the analysis of the expansion of geographical distance circle, it shows that the promotion effect of the opening of high-speed railway on the green development efficiency of cities in different circles shows an inverted U-shaped trend, and reaches the maximum at 200 km away from the central city.

Key words: High-speed railway opening, green development efficiency, DID, mediation