The invention belongs to the technical field of hydrogel, and more specifically discloses a preparation method of an interpenetrating polymer network hydrogel. According to the preparation method, reverse phase emulsion method is adopted to prepare a water-absorbent resin, crosslinking of the water-absorbent resin with polyacrylamide network is realized so as to obtain the interpenetrating polymer network hydrogel. The interpenetrating polymer network hydrogel possesses a first network structure which is formed via crosslinking and is used for maintaining the hydrogel base framework, and a second network structure used for penetrating the first network structure, so that the mechanical strength of the interpenetrating polymer network hydrogel is higher than that of common hydrogel products.