The effect of adding barley (Hordeum vulgare L.) β‐glucan (BBG) to dough on the water redistribution and the thermal properties of dough was studied by TGA and DSC. Combined with LF‐NMR to analyse the competition and redistribution mechanism of water at the 1H level. The mass loss of the dough measured by TGA was reduced by an average of 2.11% with BBG added. BBG increased the water retention of the dough, delayed the water loss process. The LF‐NMR results showed that at the same water absorption the T21 of the 3% BBG dough was longer while its T22 was shorter than those of the control. BBG has different effects on the different states of water in the dough. BBG increased the free sulfhydryl content in dough during heating, while the adverse effects of BBG on the biopolymer reactions, such as disulfide bond, could be partially relieved by regulating water content.