Abstract: The notoginseng flower buds from (Panax notoginseng (Burk.) F. H. Chen ex C. Chow) are an important medicinal and edible resource and are always used for extracting functional saponins, while the flower residue with rich dietary fiber (DF) is generally discarded. In this work, the flower residue was mixed fermented with the kefir grains and kombucha consortium to investigate the effects of fermentation parameters on the functional properties of the soluble dietary fiber (SDF) and insoluble dietary fiber (IDF) by single-factor and response surface experiments. The optimal fermentation conditions were as follows: the broth ratio of kefir grains and kombucha 2:1 (v/v), inoculation amount 8% (v/w), culture temperature was 28 ℃, and fermentation time 53 h. Under these optimized conditions, the fermented SDF (F-SDF) yield was 40.32%, showing a 78.87% increase compared to the unfermented SDF (A-SDF), and its functional group abundance had been significantly enhanced. For F-SDF and F-IDF, the water holding capacity (WHC), oil holding capacity (OHC), water swelling capacity (WSC), and cation exchange capacity (CEC) increased by 80.30% and 89.77%, 69.37% and 76.77%, 111.98% and 67.18%, and 58.82% and 122.22%, respectively. Under simulated gastrointestinal conditions, when the pH was 2.0, the adsorption capacities for cholesterol, nitrite, glucose, and sodium cholate increased by 22.67%, 21.48%, 61.18%, and 22.50%, respectively; when the pH was 7.0, the adsorption capacities for cholesterol, nitrite, glucose, and sodium cholate increased by 29.45%, 19.28%, 72.66%, and 22.61%, respectively. In conclusion, the mixed fermentation effectively modified the physical structure and functional properties of the dietary fiber derived from notoginseng flower residue. The results provide a theoretical basis for promoting the high-value application of notoginseng by-products.