The invention relates to a method for manufacturing injectable water-swelling gingival retraction paste. The method comprises the following specific operations of: preparing and mixing 1-3g of polyvinylpyrrolidone (PVP) and 20mL of aluminium chloride solution with concentration of 15%, and putting in a water bath at a temperature 70 DEG C for 30min to sufficiently dissolve; slowly adding 20-30g of kaolin and 2-3g of cross-linked polyvinylpyrrolidone (PVPP), putting in a numerical constant temperature stirrer, and sufficiently stirring at a temperature 70 DEG C under a revolving speed 100r/s to obtain the injectable water-swelling gingival retraction paste. The method for manufacturing injectable water-swelling gingival retraction paste has simple operation, good controllability, environmentally friendly and high yield; the materials used are pharmaceutical substances with high biocompatibility, the injectable water-swelling gingival retraction paste is an ideal material for implementing gingival retraction technology; the gingival retraction material obtained through the method has the advantages of convenient operation, time-saving and no wound and the like; when compared with similar products abroad, the injectable water-swelling gingival retraction paste has high price performance ratio; the problem that similar products abroad are collapsed when meeting water is overcome, with good stability in oral cavity saliva environment, the injectable water-swelling gingival retraction paste is not collapsed, and the injectable water-swelling gingival retraction paste can swell.