The interaction between oat starch and β-glucan plays a major role in the formation of oat dough. In order to explore the effects of β-glucan on properties of oat starch， β-glucan was added to oat starch with different ration. Microstructure， rheological and effect of β-glucan on starch retrogradation were studied. The results showed that with the increase of adding amount of β-glucan， the particle size of the compound system significantly decreased， oat starch/β-glucan mixed systems formed a dense， continuous honeycomb-like network structure， the enthalpy of gelatinization increased， indicating that mixed system had a good stability. Infrared spectroscopy showed that the system did not form a new group. β-Glucan could significantly reduce the hardness， increase the mixture and improve the quality of food. Pasting temperature and peak time of pastes were increased while setback value and breakdown value were reduced by adding β-glucan. The mixed system had better thermal stability and aging resistance. The mixed system was still a weak gel. Compared with the original starch， the viscoelasticity and consistency coefficient increased， and mixture was easier to shear thinning added with 5%-10% β-glucan. The solid property was the most obvious when added with 10%. When the addition amount was 15%-20%， the viscoelasticity decreased， while the shear stability of the mixed system increased. β-Glucan inhibits the long-term regeneration of oat starch when added with 10%. The research results can provide a reference for the application of the mixed system in food industry.