Abstract: This study investigated eleven first-pass reduction flours within the low-gluten wheat flour milling system. The quality characteristics of these flours were evaluated, including protein content, wet gluten content, particle size, processing precision, whiteness, farinograph properties, and gelatinization properties. Additionally, the in vitro protein digestibility of these flours for infants and young children was assessed. The objective was to compare the properties and digestibility of the first-pass reduction flours, and using digestibility as the primary criterion while considering flour quality characteristics, identify wheat flour raw materials suitable for infant cereal complementary foods. The results indicated that the ash, protein, and gluten contents of these first-pass reduction flours were relatively low. For 1M₁, 1M₂, 2M₁, and 2M₂, both damaged starch content and brightness decreased, while solvent retention capacity decreased and particle size exhibited an upward trend across their respective upper, middle, and lower streams. Water absorption and weakening degree were higher in 1M₁ and 2M₁ compared to 1M₂ and 2M₂. Peak viscosity, minimum viscosity, and final viscosity of 1M₁, 1M₂, 2M₁ and 2M₂ all showed an upward trend. In terms of in vitro static digestion rates for infants and young children, flours from the 1M₁ and 2M₁ systems demonstrated higher rates than those from the 1M₂ and 2M₂ systems. Notably, the upstream flour of 2M₁ exhibited a relatively high protein content, a high protein digestion rate, and significantly lower breakdown and setback values. Compared with the upstream flour of 1M₁, which had a similar digestion rate, the 2M₁ upstream flour demonstrated superior flour quality characteristics. Therefore, among the first-pass reduction flours, the 2M₁ upstream flour is the most suitable raw material for easily digestible infant cereal complementary foods.