The fiscal deficit, as one of the means to regulate macroeconomic operations, plays an important role in promoting digital inclusive finance and economic growth. Based on panel data from 31 provinces from 2011 to 2022, this study examines the mechanism of fiscal deficits in the impact of digital inclusive finance on economic growth. The research results indicate that fiscal deficits have a positive moderating effect and a single threshold effect on the promotion of economic growth through digital inclusive finance. The heterogeneity of the moderating effect is strong in the eastern and western regions, while there is no effect in the central region; When the proportion of livelihood fiscal expenditure is low, it is strong, but when the proportion is high, it has no effect. The single threshold effect is manifested as a non-linear characteristic of the promotion effect of digital inclusive finance on economic growth showing a first strong and then weak trend as the scale of fiscal deficits expands. Based on this, countermeasures and suggestions are proposed to implement differentiated fiscal deficits, improve the efficiency of fund utilization, and set reasonable upper limit standards for deficits, in order to fully leverage the macroeconomic regulation role of fiscal deficits.