Abstract: In this study, to mitigate quality deterioration in pre-fermented frozen red bean baozi dough (PF-FRBBD) during freeze-thaw cycles, water-soluble yeast β-D-glucan (WSYG) was employed as an additive to investigate the effects of varying WSYG concentrations on gas production capacity, viable yeast count, moisture distribution, microstructure, and thermal properties of PF-FRBBD subjected to freeze-thaw cycles. Results revealed that, compared with non-frozen-thawed samples, PF-FRBBD subjected to 6 freeze-thaw cycles exhibited a 36.6% reduction in total gas production within 120 minutes and a 96.3% decrease in viable yeast count. Concomitantly, the water loss rate and water activity increased significantly (P<0.05), while the proportion of strongly bound water decreased, resulting in a rough and porous microstructure. After 6 freeze-thaw cycles, compared to the untreated samples, the PF-FRBBD supplemented with 0.5% WSYG showed a 17.2% increase in total gas production and a 66.7% increase in viable yeast count, with significant reductions in water loss rate and water activity (P<0.05), while maintaining an intact gluten network. In the 0.5% WSYG group, the specific volume and sensory score of steamed Baozi were determined as 1.67±0.02 mL/g and 63.5±1.6 points, respectively, reflecting a rise of 9.9% and 29.3% from untreated samples. The research findings affirm that water-soluble yeast β-D-glucan can effectively improve the quality of pre-fermented frozen red bean baozi dough during freeze-thaw cycles, with the optimal addition level identified as 0.5%.