The invention discloses decaffeinated Pu'er tea and tangerine peel concentrated juice and a preparation method thereof. The decaffeinated Pu'er tea and tangerine peel concentrated juice contains the following components in parts by weight: 60-90 parts of decaffeinated fermented Pu'er tea concentrated juice and 10-40 parts of tangerine peel concentrated juice. The preparation method comprises the following steps: preparing the decaffeinated fermented Pu'er tea concentrated juice, preparing the tangerine peel concentrated juice, uniformly mixing 60-90 parts of decaffeinated fermented Pu'er tea concentrated juice and 10-40 parts of tangerine peel concentrated juice, sterilizing, and performing sterile filling at a low temperature of 4-12 DEG C, thereby obtaining the decaffeinated Pu'er tea and tangerine peel concentrated juice. The prepared decaffeinated Pu'er tea and tangerine peel concentrated juice has the caffeine content of less than or equal to 0.3wt%, and small-molecule tea polyphenol is rich in type and high in content and is easily absorbed by a human body; and the tangerine peel is unique in flavor, and the palatability and texture are enhanced, so that the product has aroma while reducing the bitter taste of tea leaves, and the requirements of specific populations can be met.