Abstract: In this study, five kinds Simiao rice (19Xiang, Meixiangzhan, Aosizhan, Xiangyaxiangzhan, Xiangzhuxiangsimiao) were milled by emery roll whitening machine under different milling time, the theoretical degrees of milling (DOM) of 0.0%, 2.0%, 4.0%, 6.0%, 8.0%, 10.0%, 12.0% were realized. Then, the milling qualities of Simiao rice were compared between reasonable milling (DOM estimated by bran degree was 2.0%-7.0%) and well milling (DOM estimated by bran degree less than 2.0%). The correlation between different milling qualities was analyzed. The results showed that when the DOM of five kinds Simiao rice increased from well milled range to medium milled range, the head rice ratio increased by 2.96%-23.70%, the germ remained ratio increased by 5.39%-165.98%, the whiteness decreased by 11.95%-51.63%. The head rice ratio, the germ remained ratio of Simiao rice decreased with the increase of DOM. Mathematical model was carried out to determine the relationship between the DOM estimated by grain weight loss and the DOM estimated by bran degree, respectively. R² of fitted curves for the models were all above 0.99. On the other hand, the results showed the mathematical models had a good fitting degree. The germ remained ratio was significantly positively correlated with the head rice ratio, and the whiteness was significantly negatively correlated with the head rice ratio (P<0.01). The germ remained ratio of the xiangyaxiangzhan were much higher than the national standard in the reasonable milled range. In the SEM images, when the degree of bran retention was about 2.00%, the ventral aleurone layer of the five kinds Simiao rice was almost removed, while a very small amount of aleurone layer remained on the dosal part. When the milling degree was well milled, the dosal aleurone layer of Xiangyaxiangzhan had been completely removed, while there was still a small amount of dosal aleurone layer for Aosizhan. The head rice ratio and the quality of product could be increased when the rice mill equipped with No.40 emery roller at a speed of 1 060 r/min. Excessive pursuit of the whiteness would lead to an increase in broken rice. Thus, reasonable milling was an effective way to improve the quality of product and the economic benefits of enterprises.