To investigate the effects of microbial solid-state fermentation on the multi-dimensional quality of mung beans, whole seeds were fermented with Aspergillus niger (fermentation temperature 26.5 ℃, inoculum concentration 8 mL/100 g). Changes in the nutritional composition, bioactive substances, antioxidant capacity of mung bean, as well as the physicochemical and digestive properties of mung bean powder during fermentation were analyzed. The results indicated that during solid-state fermentation, the levels of nutrients and bioactive substances in mung beans significantly increased (P<0.05). On day 10 of fermentation, the concentrations of protein, essential amino acids, and soluble dietary fiber were 1.13, 1.06, and 2.65 times those in unfermented mung beans, respectively. The contents of γ-aminobutyric acid, free polyphenols, and free flavonoids were 3.29, 3.42, and 1.81 times higher than those in unfermented mung beans, respectively. Additionally, with the increase in phenolic compounds, the antioxidant capacity of the alcohol extract was significantly enhanced (P<0.05). Compared to unfermented mung bean powder, the fermented mung bean powder exhibited a looser structure, higher solubility, and increased water and oil holding capacities. Rheological analysis showed a decrease in the viscoelasticity and an increase in the fluidity of the fermented mung bean powder. The anti-digestive properties of mung bean powder were enhanced after fermentation. On day 10 of fermentation, the proportion of resistant starch was 21.16%, and the eGI value was 39.99. This study demonstrated that solid-state fermentation with Aspergillus niger can improve the nutritional quality of mung beans, enhance the physicochemical and functional properties of mung bean powder. The findings are expected to provide a theoretical basis for the comprehensive processing and utilization of mung beans and the development of high-quality mung bean fermented foods.