<p>In this research, natural inulin phosphate monoesters (PFI) were prepared through phosphorylation modification of natural inulin (FI). The effects of PFI at various addition levels (0%, 2.5%, 5%, 7.5%, and 10% on flour weight basis) on the quality characteristics of strong wheat dough were systematically investigated to elucidate the mechanism of action. The results indicated that the addition of PFI significantly improved the rheological properties of the strong wheat dough. As the PFI addition level increased, both the storage modulus (G′) and loss modulus (G″) of the strong wheat dough gradually increased. Low-field nuclear magnetic resonance (LF-NMR) analysis demonstrated that the addition of PFI significantly modified the water distribution in the strong wheat dough. As the PFI addition level increased, the content of weakly bound water progressively rose. At the protein structure level, the addition of 2.5% PFI significantly increased the content of disulfide bonds and β-sheet in the gluten protein, enhancing the cross-linking interactions between protein molecules. CLSM observations further revealed that the addition of 2.5% PFI resulted in a more continuous and compact gluten network structure. The regulatory mechanism of PFI on the quality of strong wheat dough was elucidated from multiple perspectives in this study, providing a crucial theoretical basis and a technical pathway for the development of functional baked products with high dietary fiber content.</p>