Abstract: This study aims to construct bran starch-fatty acid nanocomposite particles (BSN-CX, where X denotes the number of carbon atoms in the fatty acid) using wheat bran starch as the raw material, and to investigate the effects of modification with saturated fatty acids of different carbon chain lengths (C10~C18) on the particle structure and emulsifying properties. The differences in the structural properties and emulsifying properties of the nanoparticles modified with different fatty acids were systematically analyzed by characterizing the complexing index, particle size distribution, microstructure, crystalline structure, thermodynamic properties, and three-phase contact angle. The analysis also included the evaluation of Pickering emulsions stability. The complexing index exhibited a decreasing trend followed by an increase with the elongation of the fatty acid carbon chain, with BSN-C10 demonstrating the highest complexing index at 75.03%. X-ray diffraction results indicated that the relative crystallinity of the V-type structure progressively decreased with increasing fatty acid carbon chain length, with BSN-C10 showing the highest relative crystallinity of the V-type at approximately 18.54%. Scanning electron microscopy (SEM) and particle size analysis revealed that both BSN and BSN-CX presented a nanoscale aggregated distribution, characterized by rough surfaces and variable sizes. Thermodynamic property analysis confirmed BSN-CX belonged to Type I starch-lipid complexes. Three-phase contact angle measurements demonstrated that the starch granules modified by fatty acid complexation had significantly enhanced hydrophobicity and improved emulsifying capacity. Characterization of the prepared Pickering emulsions indicated that BSN-C10, BSN-C12, and BSN-C16 exhibited outstanding performance in terms of emulsion separation index, storage stability, and centrifugal stability over a 15-day storage period. A comprehensive analysis concluded that BSN-C10, with excellent structural properties and emulsifying properties, is the most suitable emulsifier for Pickering emulsions. This study provides a theoretical foundation for expanding the applications of bran starch and developing novel food-grade Pickering emulsion systems.