Chestnut starch acetate (CSA) was prepared by attaching acetic anhydride groups on chestnut starch (CS) molecules. The process conditions for the preparation of CSA were optimized through single-factor testing and response surface analysis. The optimal conditions were as follows: acetic anhydride content 7%, time of reaction 92 min, temperature 33°C, and pH 8. The actual average apparent viscosity of CSA was 480.53 ± 0.29 mPa·s, which was 109.38% higher than that of natural CS. Fourier transform infrared spectroscopy analysis showed that the hydroxyl group was replaced by the acetyl group on the acetic anhydride. The X-ray diffraction analysis revealed that the crystal form of CSA was type C even after modification. As observed by scanning electron microscopy, the surface of some CSA granules presented different degrees of sag, breakages, and wrinkles. The water retention analysis of the dough revealed that the addition of CSA in the dough was 6%, and the dough had the strongest hydrophilicity and the best water retention. Further, a high number of freeze-thaw cycles reduced the water retention of the dough. The texture characteristics analysis indicated the addition of CSA in the raw dough was 6%–9%, which improved the firmness and toughness of the frozen-thawed dough.