【Objective】The impact of high-speed trains on urban green technology innovation is an important research direction in the study of the impact of high-speed trains on regional innovation. In order to study the impact of high-speed railway on the "quality and quantity" of urban green technology innovation, 【Method】this paper establishes a multi-period DID model and discusses how high-speed railway operation affects urban green technology innovation based on the panel data of 41 cities in the Yangtze River Delta urban agglomeration from 2004 to 2019. 【Result】The results show that the operation of high-speed trains can effectively improve the "quality and quantity" of urban green technology innovation in the Yangtze River Delta. Through the mechanism test, the opening of high-speed trains can affect urban green technology innovation by strengthening economic agglomeration and venture capital; The operation of high-speed trains has the heterogeneity of city size and region, and the operation of high-speed trains has a significant impact on large cities and small and medium-sized cities. 【Conclusion】This study systematically expounds the connection between the operation of high-speed trains in the Yangtze River Delta region and the "quality and quantity improvement" of urban green technology innovation, and the conclusion is still valid after the robustness test.