Modified sweet potato flour is sweet potato flour that has been enhanced to maintain and improve its quality, thereby reducing the overall consumption of sweet potato flour in Indonesia. Muffins, being a type of quick bread that requires only a small amount of gluten, are highly suitable for use with modified sweet potato flour. This research was carried out in two stages: Stage I involved the modification of sweet potato flour, and stage II consisted of formulating a mixture of wheat flour and modified sweet potato flour. The research employs a non-factorial Completely Randomized Design (CRD) for both of these two stages and the determine of the best treatments are conducted using De Garmo effectiveness index method. The modified flour (annealing, instant yeast fermentation, LAB fermentation, and acetic acid) was analyzed for various quality parameters. Once the best method for modifying sweet potato flour was determined, the second stage involved the preparation of muffins. The muffin (100:0, 75:25, 50:50, 25:75, and 0:100) were also analyzed for various quality. The final results indicated that the J3 treatment (LAB fermentation) was the most effective for modifying the flour, and the F2 treatment (75:25 ratio) was the best formulation for muffins.