Based on the sample of 271 cities at prefecture-level and above in China from 2011 to 2019， this paper uses the system GMM model to explore the impact of digital finance on the quality of urban innovation. The results show that digital finance plays a significant positive role in promoting the quality of urban innovation， and the promotion effect are in the following order： coverage， depth of use and digitalization. In terms of heterogeneity of city size， the relationship between digital finance and innovation quality in big cities， mega-cities and mega-cities shows a significant positive promoting effect， while in small and medium-sized cities it shows a negative inhibiting effect. In terms of the heterogeneity of urban hierarchy， the relationship between digital finance and innovation quality in the first-tier， second-tier， third-tier and fourth-tier cities all show significant positive promoting effect， while in the fifth-tier cities it shows a negative inhibiting effect. In terms of urban regional heterogeneity， the relationship between digital finance and innovation quality in the eastern， central and western regions shows a significant positive promoting effect， in which the central region shows a greater promoting effect， followed by the western region， and the eastern region is relatively small. To further promote the development of digital finance， we should formulate and improve policies and implementation rules in the related fields of digital finance to ensure the docking of digital finance with enterprises， especially small and medium-sized enterprises； strengthen the reform of stock financial institutions and the expansion of incremental financial institutions， broaden the coverage and enhance the depth of use of digital finance， and give full play to the advantages of digital finance in region， time and space； and implement policies according to regions and cities to promote the balanced development of digital finance.