The invention discloses a bitterless citrus reticulata juice and a preparation method thereof. The preparation method comprises the following steps: removing orange fibers and carpellary membranes from citrus reticulata pulp through an acid-alkali method, separating the citrus reticulata pulp from the citrus reticulata seeds, and finally subjecting the obtained citrus reticulata pulp to treatments of juicing, homogenizing, and sterilizing so as to obtain the bitterless citrus reticulata juice. The preparation method is simple and practicable, the instruments and equipment used in the preparation method is easily available, thus the preparation method has a low cost, moreover the preparation method can be applied to massive production, so the preparation method is easy to popularize. The prepared citrus reticulata juice is bitterless, has a flavor similar to that of a high-quality orange juice product, and the obtained citrus reticulata pulp can be used to produce juice drinks containing citrus reticulata pulp.