Abstract: In order to investigate the mechanism of changes in the fiber breaking strength of high-moisture textured vegetable protein（HMTVP）, HMTVP was prepared in this study via a twin-screw extruder with different starch addition amounts and screw rotational speeds. The key factors affecting the fiber breaking strength were revealed by analyzing the changes in the microstructure, chemical bonding, intermolecular forces, and the secondary structure of proteins in HMTVP. The results showed that the fiber breaking strength of HMTVP showed a tendency of decreasing and then increasing with the increase of starch addition and screw speed, with minimum values of 0.70 N（at 7.5%） and 0.73 N(at 280 r·min^-1), respectively. The changes in free sulfhydryl and disulfide bond contents were closely related to the fiber breaking strength. With the increase of screw speed and starch content, the β-sheet content in HMTVP exhitited an overall increased, while β turn content decreased, indicating a transition from a disordered to an ordered protein molecular structure. The relationship model between intermolecular forces or chemical bonds and the fiber breaking strength of HMTVP was established by logistic function fitting. It provides theoretical support for precisely regulating the process parameters of starch addition amount and screw rotational speed and offers a theoretical basis for the development of HMTVP products with meat-like fiber strength.