The present invention relates to a black garlic manufacturing method through fermentation, which can effectively solve the problem of peculiar smell or discomfort of garlic. The technical proposal is as following. Firstly, far infrared heating device is used to produce anion. Secondly, garlic is marinated in the garlic fermentation inducing medium. Thirdly, after the garlic is fished out, the garlic is put into the far infrared heating device. Fourthly, the garlic is heated and fermented step by step. And lastly, the black garlic is made. The garlic fermentation inducing medium is made by the following components based on weight-volume percent: salt 8.6 percent, ethanol 4.1 percent, amino acids 3.1 percent, protein 0.6 percent, sugar 12.4 percent, ash content 7.9 percent, lipid 0.02 percent and water for the rest. The present invention has simple method, good garlic processing effect. After procession, the garlic has no peculiar smell, is convenient to eat, has high nutritive value, is used widely, and has great economic and social benefits.