Abstract: In order to improve the hydrophobicity of tapioca starch, and used it as a granular emulsifier to improve the emulsification properties of myofibrillar protein (MP). In this study, a hydrophobic modification of native tapioca starch (NTS) by octenyl succinate anhydride (OSA), which produced ocentyl succinic tapioca starch (OSTS) with different modification levels and degrees of substitution (DS), and the compound emulsions were prepared using OSTS and MP. The structural changes of the OSTS were analyzed by XRD, FT-IR, SEM, and PLM, and the emulsion index (EI), emulsifying activity index (EAI), emulsion stability index (ESI), Zeta-potential, particle size distribution, sulfhydryl content, and interface protein content of the emulsions were determined. The results showed that the hydrophobic groups were successfully introduced in the tapioca starch molecules, and the hydrophobic modification treatment had basically no effect on the crystal structure type of the tapioca starch particles. The EAI and ESI of the OSTS-MP compound emulsions improved significantly (P<0.05) with increased starch modification levels and DS values, which of the 3.0% OSTS-MP compound emulsion had the best stability. The interaction of starch and MP in the compound emulsion impacted on the spatial structure of MP, both of them had a competitive adsorption effect at the emulsion droplet interface, and which of these were enhanced with modification levels and DS values. The results obtained provided a theoretical basis for the application of OSTS in emulsified comminuted meat products.