Natto is a traditional fermented food from Japan that is made from soybean fermented by Bacillus subtilis natto. The mucus drawing length of natto determines the sensory quality of natto, and there are differences in the mucus drawing length and sensory quality of natto fermented with soybeans with different contents of soluble sugars. In this study, soybeans with different contents of soluble sugars were used to ferment natto, and the differences and correlations between the mucilage composition, the mucus drawing length and the sensory quality of natto were investigated. The contents of oligosaccharides and total sugars in soybean were significantly positively correlated with the mucus drawing length (R = 0.921, R = 0.956), and the correlation between the drawing length of mucilage and total sugars was stronger. Fermenting soybeans with high contents of total sugars could make mucus drawing of natto longer. The contents of oligosaccharides and total sugars in soybean were significantly positively correlated with the sensory index score (R = 0.886, R = 0.925). The natto fermented from soybean with high contents of soluble total sugars had better overall sensory quality. Soluble sugars had a positive influence on mucus drawing length and sensory quality of natto.