This study revealed the effect of protein-polysaccharide extracted from Auricularia auricula-judae fruiting bodies (AAP) on the textural properties and microstructures of Chinese wheat noodles. In addition, the underlying mechanisms were explored. AAP is a protein polysaccharide with a molecular weight of more than 104 Da. According to the RVA and DSC results, AAP increased the pasting (PV and FV) and thermal properties parameters (To, Tp, and Tc) of wheat starch. AAP also significantly increased β-sheet and β-turn (p < 0.05) in the secondary structure of gluten but decreased α-helix content and the sulfhydryl group. Additionally, AAP increased the hardness, adhesion, tensile force, and tension distance of wheat noodles and significantly reduced the cooking yield and cooking loss (p < 0.05). The cross-linking of protein molecular networks was promoted to enhance the compact microstructure of the dough detected by CLSM. Moreover, the water status was changed by AAP, forming more combined water in contact with gluten and starch through hydrogen bonds. A theoretical basis for the positive effects of mushroom polysaccharides on the quality of wheat food from the perspectives of physicochemical characteristics of wheat starch and gluten was provided in this study. •AAP is a water-soluble protein-polysaccharide which acted as a food thickener to improve the quality of noodles.•AAP changed the gelatinization and thermodynamic characteristics of starch, and gluten secondary structure.•Textural and cooking properties improved along with the increasing AAP below 1.5%.•Internal microstructure of dough became more compact after adding AAP.•Moisture in noodles was redistributed with different content of AAP.