Abstract: In this paper,different particle size of the crushing treatment and three methods of aging treatment were applied,that were frying,baking and microwave,and the effect of aging treatment of millet flour to gelatinization characteristics and the stability of particle size of millet flour in water system and milk system when brunching were studied. The results showed that the method of aging treatment and particle size had an impact on the stability of millet flour in both water and milk,and also had an impact on the gelatinization characteristics of millet flour. Compared with the untreated control sample,the three treatments had different effects on the gelatinization characteristics of millet flour. Microwave treatment had a relatively weaker effect on the gelatinization characteristics of millet flour. The tolerance of temperature and shear stress of baking millet flour was the strongest. The regenerated ability of fried millet flour was the strongest. The particle size had a great influence on the gelatinization and thermal stability of millet flour. The stability of brunching stability increased with the decreasing of the particle size. The caking rate and the water-soluble stability decreased with the decreasing particle size. The stability of millet flour in water and milk showed the same trend,but the variation of millet flour in milk was even more pronounced.