This article aims to improve the stretching quality of the flat noodles products by optimizing the key processes such as refining, formula and steaming on the breaking distance of whole grain flat noodles. The results show that the breaking distance of whole grain flat noodles prepared by backfilling rice bran is significantly better than that of whole rice refining. Meanwhile, scanning electron microscopy analysis shows that the grains of backfilled whole grain rice slurry are small, fine and uniform. The particle size results show that 83.91% of the particles are below 10 μm, and 14.93% of the particles are between 10 μm to 100 μm, while only 1.16% of them are larger than 100 μm, which is close to polished rice slurry. To further improve the stretching quality, the rice bran to be backfilled is selected. At the same time, the effect of adding soy protein isolate, guar gum, konjac mannan, cassava starch, gluten and other ingredients on the breaking distance of flat noodles is compared. The stretching quality of whole grain flat noodles prepared from homologous defatted rice bran and added soybean protein isolate is the closest to that of ordinary rice noodles. The material-to- liquid ratio of the optimized steaming process is 1∶1.4 (g∶mL) and the products are steamed for 9 min.