In the process of drying, uneven drying rate will lead to the decline of grain quality, including the increase of crackle ratio, the destruction of the edible quality. In this paper, based on PAGE model the numerical simulation method suitable for circulated rice drying process of constant rate was developed and circulated rice drying process of constant rate was built. The simulation software of circulated rice drying process of constant rate was developed by MATLAB graphical interface language. Based on software setting of parameters including initial moisture, drying rate, hot air temperature, ambient temperature and ambient humidity, the simulation experiment of circulated rice drying process of constant rate could be conducted, the curves of grain moisture, grain temperature and drying rate could be drawn. The simulation experiment of rice circulation drying of constant rate was conducted, and the simulation results could served as the application of constant drying rate circulation drying.