New quality productive forces bring new opportunities for financial digital transformation and economic upgrading. The age-old topic of the relationship between financial development and economic growth is becoming more and more time-honoured. Based on the combination of the Digital Inclusive Finance Index and the Digital Transformation Index of Commercial Banks, a new measurement of the development level of provincial digital finance is conducted. Furthermore, based on the panel data of 31 provinces in the mainland of China from 2011 to 2021, the effect of digital financial development on the real economy is empirically examined using the threshold model. The study finds that: Firstly, the impact of digital finance on the real economy is characterized by a two-threshold non-linear relationship. The level of digital finance development can strongly and significantly promote real economic growth when it is less than the first threshold, play a significant inhibiting role when it rises between the first and second thresholds, and the inhibiting role of digital finance further attenuates after the second threshold is crossed, but still remains significant; Secondly, the regional heterogeneity analysis shows that the impact of digital finance on the real economy in the eastern, central and western regions all show single-threshold characteristics, but with different effects. Digital finance in the eastern region significantly inhibits real economic growth on both sides of the threshold, and the inhibiting effect decays after crossing the threshold. Digital finance in the central region has a significant facilitating effect on the real economy when it is less than the threshold and a significant inhibiting effect when it is greater than the threshold. In the western region, digital finance has a significant inhibiting effect on the real economy when it is less than the threshold and a non-significant inhibiting effect when it is greater than the threshold; Thirdly, new quality productive forces theory reveals the intrinsic power source of real economic growth from the three dimensions of capital allocation, scientific and technological innovation, and labour supply respectively. Mechanism tests based on new quality productive forces theory show that capital allocation efficiency and labour productivity play an intermediary transmission effect, but technological innovation efficiency does not have an intermediary effect. The study provides a theoretical basis for the adjustment of digital financial development strategy and the choice of path for digital financial services to the real economy, and is of policy revelation significance in guiding the coordinated development of digital finance and the real economy and promoting the development of new quality productive forces.