Objective:Study on broken characteristics of brown rice in rice milling chamber.Methods:The mechanical tests of brown rice were carried out by universal material testing machine, and the breaking cracks were observed by digital microscope.Results:Brown rice will undergo the alternating process of yield stage and strengthening stage until fracture. Under the action of extrusion load, cracks were generated at the internal microvoids, and the rapid propagation of cracks caused the breakage or fracture of rice grains. Under three-point bending and shear loads, cracks were generated from the bottom of the support end and extended to the front. The compressive deformation resistance of brown rice was the largest, followed by the three-point bending deformation resistance, and the shear deformation resistance were the smallest. Compared with extrusion load, the breaking strength and breaking energy of brown rice under three-point bending and shear load were smaller.Conclusion:When designing the structure of rice mill, the influence of bending and shearing on brown rice should be minimized. Mechanical properties of japonica brown rice are better than indica brown rice under the same conditions.