The invention discloses a preparation method of black garlic juice and black garlic powder, and belongs to the technical field of deep processing of food products. The preparation method is characterized in that whole black garlic with peel is utilized as a raw material; water is utilized as an extraction solvent; and a water-soluble component of black garlic is extracted through the processes ofcrushing and extraction, squeeze and solid-liquid separation. The extracted liquid component can be prepared into black garlic juice or concentrated black garlic juice for liquid food ingredients such as black garlic beverages, black garlic vinegar, black garlic soy and the like, and residual garlic residues and garlic peel are prepared into ultra-micro garlic powder rich in amino acids and dietary fiber through the processes of drying and ultra-micro crushing. The ultra-micro garlic powder can be utilized as an ingredient of instant seasoning powder, local-flavor cakes and the like.