The invention discloses a water-soluble wafer adhesive which is prepared from the following four components in parts by weight: 100 parts of acacia gum, 160-185 parts of pure water, 15-30 parts of aluminum alum and 15-25 parts of glycerinum. The preparation method comprises the steps of (a) weighing pure water with the mass being equivalent to mass of the acacia gum and heating the pure water to be 60 DEG C or above, adding powdery acacia gum, mixing, and stirring evenly to form gelatinous acacia gum; (b) mixing the aluminum alum with the remaining pure water to prepare an aluminum alum solution; (c) mixing the aluminum alum solution with the gelatinous acacia gum evenly; and (d) finally pouring glycerinum into a mixed solution obtained in the step (c) and stirring evenly to obtain the water-soluble wafer adhesive. The water-soluble wafer adhesive is capable of replacing currently used paraffin, can be bonded and solidified at room temperature, and is small in stress, simple to clean, environmentally friendly and low in cost.