The invention discloses a vagina-retained boric acid preparation and a preparation method thereof. To be specific, optimally, the vagina-retained boric acid preparation is mainly prepared from methylparaben, propyl hydroxybenzoate, potassium sorbate, chitosan, glycerol, carbomer 974, polycarbophil, boric acid and purified water. The performance of the vagina-retained boric acid preparation is mainly characterized in that the preparation can be retained in vagina and release boric acid which serves as a bacteriostasis element, and it is proved through experiments that by the adoption of the gel, the high boric acid concentration in vagina liquid can be reached and maintained for a long time. The invention further discloses the preparation method of the vagina-retained boric acid preparation. Furthermore, it is proved through tests that the dynamic viscosity of the vagina-retained boric acid preparation is greater than 100000 centipoises, the pH value ranges from 2 to 5, the water retention property is good, no allergenicity exists, no vagina irritation exists, and the bacterium and fungus inhibition effect is achieved.