Report on protein cross-linking mechanism of soy-wheat Chinese steamed bread treated with azodicarbonamide (ADA) was less while it was known as quality improvement agent of wheat flour. The content of free thiol (—SH) was determined by DTNB method. Meanwhile, size-exclusion high performance liquid chromatography (SE—HPLC) and confocal laser scanning microscope (CLSM) were used to analyze the content of sodium dodecyl sulfate extractable proteins (SDSEP）and gluten network respectively. In addition, the specific loaf volume of soy-wheat Chinese steamed bread was determined by rapeseed displacement method. TPA was used to test the texture and the software Image J was applied to analyze the pore structure of soy-wheat Chinese steamed bread treated. The result showed that ADA reduced the content of —SH, which meant that the —S—S— content was increased. The SDSEP content was decreased and the extent of protein cross-linking was increased. ADA could promote proteins aggregating into dense and uniform network. Gelatinized starches were warped by protein framework. Moreover, ADA made no significant effect on specific loaf volume and also increased the hardness, gumminess and chewiness. The gas cell counts were increased, and average size and average friction of gas cells were decreased, along with the forming of uniform, dense and small pore structure. In combining the greater protein polymerization with the better quality characteristics of soy-wheat Chinese steamed bread, it indicated that there was inner relationship between protein cross-linking and the final quality characteristics of soy-wheat Chinese steamed bread.