In the context of digital finance and based on the characteristics of the high-quality development of SMEs in China, this paper investigates the influence of digital finance on the high-quality development of SMEs and explores their mechanism of influence. A panel econometric model and mediation model are used to evaluate the data of 581 SMEs in China from 2011 to 2020. The results show that digital finance has a significant role in promoting the development quality of SMEs. Heterogeneity analysis shows that the promotion effect of digital finance is more obvious in central and western regions, non-heavy pollution industries and non-state-owned SMEs than that of other SMEs. Further analysis shows that digital finance improves the efficiency of financial resource allocation, which in turn promotes the high-quality development of SMEs. After applying a test of robustness, the results proved significant.