In recent years, textured-vegetable-protein-based meat analogs have received more and more attention. The protein digestibility of plant-based meat analogs is still unclear. Sodium bicarbonate is a commonly used additive in the preparation of textured proteins. In order to explore the effect of sodium bicarbonate on the fibrous structure and protein digestibility of textured protein, textured wheat proteins containing 0, 0.05%, and 0.1% (mass fraction of dry powder) sodium bicarbonate were prepared. The fibrous structure was analyzed by measuring the bulk density, texture properties, degree of texturization, microstructure, and protein-protein intermolecular interactions of the samples. The results showed that with the increase of sodium bicarbonate mass fraction from 0 to 0.1%, the bulk density, hardness, and degree of texturization of the textured wheat protein decreased gradually, and the gaps between fibers became larger when the fibers became thinner. After in vitro oral and gastric digestion, the digesta particle size of three textured wheat proteins increased with the increase of sodium bicarbonate concentration (P>0.05). After the simulated small intestinal digestion, the particle sizes of the digestion products of three textured wheat proteins were similar (P>0.05). After 30 min of gastric digestion, the band intensity of protein with relative molecular weight less than 14 300 in three samples declined with the increase of sodium bicarbonate mass fraction. After the in vitro digestion, the content of soluble nitrogen in digesta increased with the increase of sodium bicarbonate mass fraction (P<0.05). These results suggested that the protein digestion rate and degree of textured wheat proteins gradually increased with the increase of sodium bicarbonate mass fraction. After digestion, the total free amino acids obtained released from three textured wheat proteins were （39.53±0.56）, （41.56±0.59）, and （44.85±0.39） mg/g of digesta, respectively. The greater extent of proteolysis in the textured wheat proteins containing the higher mass fractions of sodium bicarbonate might be due to the thinner fibers and more fiber gaps, which promoted the proteases to interact with the cleavage sites.