To improve the quality characteristics of mung bean noodles and develop a legume staple food with a low glycemic index (GI), noodles were prepared using different proportions of mung bean ultrafine powder and wheat flour. The sensory quality, rheological properties, cooking characteristics, texture, microstructure, and starch components of the noodles were evaluated, and the GI value of the noodles was determined through human testing. The results indicated that the sensory score of the noodles was higher when 30% or 45% mung bean ultrafine powder was added. Rheological analysis showed that a higher proportion of mung bean ultrafine powder contributed to higher storage modulus (G') and higher loss modulus (G") of the dough, indicating certain levels of viscoelasticity. When 45% green bean ultrafine powder was used, the starch particles were tightly wrapped, and the internal microstructure of the noodles was relatively dense and uniform, with a hardness of 11.58 N, elasticity of 1.35 mm, cooked breakage rate of 4.34%, and satisfactory cooking quality. The addition of mung bean ultrafine powder effectively increased the content of slowly digestible starch and resistant starch in the noodles and reduced the estimated GI value of the noodles. Human blood glucose testing revealed that the GI value of noodles with 45% mung bean ultrafine powder was 49.93, classifying the noodles as low GI food. This study is of great significance for upgrading the deep processing technology of mung beans and developing healthy low-GI staple foods.