Abstract: Niandoubao is a famous traditional specialty food in Northeast China. Developing excellent starter for Niandoubao is an effective and crucial method to address the issue between traditional natural fermentation processes and modern production standards. By screening the fermentation properties of 10 groups of composite strains (numbered A-J) and comparative analyzing the various physicochemical and sensory properties of 6 groups of Niandoubao (numbered NDB-B, NDB-C, NDB-D, NDB-J, NDB-RG and NDB-SF), the influence of 4 groups of composite strains on the physicochemical properties of proso millet Niandoubao were explored. The fermentation experiment results showed that the composite strains in groups B, C, D, and J in the 10 starter exhibited good synergistic growth and acid production ability in both simulated dough medium and proso millet sourdough. Therefore, these 4 groups of composite strains were selected for the production of proso millet Niandoubao. The quality evaluation results of Niandoubao showed that compared with artificially acidified and naturally fermented Niandoubao, the chroma, digestion, fructan, phytic acid, texture, and sensory properties of 4 groups of composite strains Niandoubao were improved to a certain extent. Among them, Group B composite strains Niandoubao had the highest b* value (42.92), Group D composite strains Niandoubao had the lowest fructan content (5.55 g/100 g), and group J composite strains Niandoubao had the best comprehensive physicochemical quality. In summary, these results indicated that the composite strains in groups B, C, D, and J significantly improved the various physicochemical properties and sensory qualities of Niandoubao. Among the 10 groups of composite strains, the composite strains in group J were the best candidate starter for proso millet Niandoubao. These results provide excellent and key starter strain resources for the industrialization, standardization, and modernization of proso millet Niandoubao production in the future.