The invention mainly relates to the field of food processing technology and discloses a fermentation method of a konjak beverage. The fermentation method comprises the following steps: raw material crushing, raw material enzymolysis, primary fermentation, secondary fermentation, third fermentation, and nutrition strengthening and packaging. The method is simple and is suitable for batch fermentation production. The konjak beverage is sour and sweet and proper, has aromatic flavor, has moderate viscosity, has stable state, and is fine and smooth. Deep processing ways of konjak are increased. Economic income of farmer households is raised by 13.5%. Multiple fruits and vegetables enrich the color of the beverage and increase fragrance and nutrients. Absorption is promoted, body is strengthened, and diseases are minimized. After enzymolysis of fruits and vegetables, microstructure can be decomposed. Thus, extraction rate is raised, fragrance and nutrition of the beverage are increased, health-care function is enhanced, the gastrointestinal function is increased, toxin is expelled and skin is beautified, and resistance is enhanced. After addition of konjak, natto fermentation is carried out. Therefore, the tradition that natto is only soybean is changed, content of nattokinase in the beverage is increased, toxicity of konjak is reduced, and the beverage's function of protecting heart and cerebral vessels is increased.