Abstract: In order to solve the problem of quality decline of frozen whole wheat bread after reheating, Bread samples with different whole wheat flour additions were frozen at -18 ℃. The effects of natural thawing, steam reheating, microwave reheating and microwave steam reheating on bread quality were systematically compared. The effects of different reheating methods on gluten protein structure and the quality and flavor of bread were investigated by Fourier transform infrared spectroscopy (FTIR), fluorescence spectroscopy, scanning electron microscopy (SEM), low field nuclear magnetic resonance (LF-NMR), and GC-IMS. The analysis of texture characteristics of whole wheat bread showed that steam recuperating energy effectively maintained the texture characteristics of frozen whole wheat bread, and its hardness index was the best (3 032.86 N). The structural characterization showed that steam reheating treatment significantly reduced the content of -SH in gluten protein of whole wheat bread (P<0.05), promoted the oxidation of free -SH in gluten protein to form disulfide bonds, and significantly improved the elasticity and resilience of the product (P<0.05). Natural thawing treatment promotes protein aggregation behavior by maintaining the electrostatic repulsion of gluten proteins. Hydrophobic analysis showed that as the amount of whole wheat flour (WWF) added increased, the surface hydrophobicity of gluten protein significantly improved (P<0.05). This is due to the unstable gluten network structure caused by WWF during freezing, which further exacerbated the exposure of hydrophobic groups after reheating; Among different reheating methods, microwave reheating exhibits low hydrophobicity due to short-term high temperature and starch gelatinization masking hydrophobic groups, while steam reheating expands the gluten network through hot steam and presents higher surface hydrophobicity. The scanning electron microscope showed that most of the starch particles in the whole wheat bread naturally thawed after frozen storage were exposed outside. Compared with microwave reheating, the gluten network and starch particles in the steam reheating and microwave steam reheating bread wrapped more closely with each other. Grain size analysis showed that under microwave reheating conditions, the grain size of gluten protein of whole wheat bread of 0WWF, 50WWF and 100WWF reached the minimum value, which were 558.50, 592.86 and 615.30 respectively. The microwave steam composite treatment exhibits unique advantages and can effectively alleviate the conformational changes of whole wheat proteins caused by the freezing process. The analysis of intrinsic fluorescence spectra of proteins showed high fluorescence intensity in both microwave and steam reheating, indicating that microwave steam reheating is a relatively mild treatment method. At the same time, the results of LF-NMR analysis showed that high proportion of whole wheat reduced the free water content, and more water existed in the bound state, indicating that microwave reheating and microwave steam reheating were conducive to maintaining the water quality of whole wheat bread. In addition, the results of flavor analysis confirmed that steam reheating had little effect on the flavor of whole wheat bread; Microwave reheating and microwave steam reheating can reduce the concentration of irritating flavor substances such as diethylene glycol dimethyl ether, benzaldehyde, ethylbenzene, butyraldehyde, and 2-hexanone, while increasing the concentration of fruity flavor substances such as propyl propionate and 3-methylethyl butyrate. The sensory evaluation results showed that the microwave steam reheating method could effectively maintain the color, shape and taste quality of whole wheat bread with different amounts of whole wheat flour (0WWF, 50WWF, 100WWF), especially when 100% whole wheat flour was added, through the synergistic effect of microwave rapid internal heating and steam humid environment; Microwave reheating has higher scores in appearance and odor dimensions due to its advantage in heating speed, but the overall quality is still better in the microwave steam group. This study provides an important theoretical basis for optimizing the reheating process of frozen whole wheat flour products.