Abstract: Solubility and viscosity of water soluble starch obtained from indica rice with different mechanical milling time were studied and milling kinetics equations based on solution ratio and kinematic viscosity were established. Results indicate that solubility and kinematic viscosity can be described accurately by chemical reaction kinetics model and quadratic equation, respectively. When the ball milling time go by, the kinematic viscosity for water solubles first increase and then decrease at 25℃, and those at 100℃ decline exponentially. Solubility and viscosity of milled starch are affected remarkably by water content of starch. The change rate constant of solubility for milled starch with lower water is higher and the maximum of viscosity can be reached more quickly. The establishment of milling kinetics model has a great meaning on forecasting of milling effect and determining milling parameter.