Mung bean is one of the legumes which is abundant in Indonesia and rich in nutrients. In this research, mung bean juice with sucrose and skim milk was fermented with lactic acid bacteria to produce a fermented beverage. S. thermophilus, L. acidophilus, and S. thermophilus were used as starter. The research was started by determining the bacterial growth phase. The log starter for S. thermophilus was 5 hours, L. acidophilus was 16 hours, and L. plantarum was 11 hours. The objectives of the preliminary research was to determine the most suitable skim milk concentration and combination starter. The result showed the most suitable skim milk concentration was 6% while the most combination starter was 2:2:1 (S. thermophilus : L. acidophilus : L. plantarum). This result was used in the main research to determine the most suitable fermentation condition. In main research the most suitable fermentation condition was anaerob condition. The final product was analyzed for proximate and functional component by GC-MS method. The mung bean fermented beverage contain moisture (89,19%), ash (0,77%), protein (2,82%), fat (3,40%), and carbohydrate (3,82%). The functional component are α-pinene, eucalyptol, verbenone, benzoic acid, camphene, myristicin, β-sitosterol, stearic acid, linoleic acid, α-humulene, dan squalene.