Abstract: Provided is a preparation method of composite juice mixed by noni fruit and blueberry, which includes the following steps: a noni fruit pre-fermentation, a blueberry pretreatment, a composite fruit juice fermentation, a filtration and a centrifugation. The prepared composite juice mixed by noni fruit and blueberry has a clear and transparent form, no precipitation, uniformity, no suspended matter, rich blueberry aroma, not pungent, soft taste, moderate sweet and sour, purple luster and translucent.