Objective To address the challenges of retaining the germ in rice with remained germ, balancing nutrition, sensory qualities, and palatability.Methods A technical design proposal for a flat grinding type germ-remained rice milling machine is introduced, which combines active grinding with a flat grinding belt and passive grinding with a flexible blade group. The milling process involves rolling and grinding the rice grains on a flat surface to achieve precise, layer-by-layer grinding. The approach employs multiple flexible processing stages combined with appropriate grinding to ensure a high germ-remained rate and good whiteness of the rice. Northeast China-produced japonica rice is used as the test material, with germ-remained rate and rice whiteness as the quality indicators in orthogonal experiments.Results The optimal processing parameters for rice with remained germ are flat grinding belt speed of 8 m/s, rubber spring load of 548.8 N on the blade group, and three grinding times. The first time uses a 180 mesh flat grinding belt, and the second and third ones use a 240 mesh flat grinding belt.Conclusion After applying the optimized process, the final product achieves a germ-remained rate of 89.9% and a whiteness of 40.1%.