The invention relates to a high-molecular water-absorbent resin, a composite absorbent core and a preparation method of the water-absorbent resin. The preparation method of the water-absorbent resin comprises the steps that acrylic acid, a crosslinking agent and a hydrophobic polymerization monomer are mixed with water, a water-absorbent resin dispersion liquid and an antibacterial deodorizing additive are added, nitrogen is introduced to remove oxygen, and a mixed solution is obtained; an initiator is added into the mixed solution to initiate a reaction to obtain resin gel; the resin gel is subjected to granulation, neutralization, drying, grinding and sieving in sequence to obtain the water-absorbent resin. The composite absorbent core comprises an upper water permeable dry layer, an intermediate water absorbing layer and a lower water permeable dry layer in sequence from top to bottom; the intermediate water absorbing layer comprises at least one layer of a network structure, each network structure is formed by interweaving the upper water permeable dry layer and the lower water permeable dry layer through a cross contact point bonding method, and the water-absorbent resin is distributed in the network structures. The composite absorbent core has a sufficiently fast water absorption rate and a sufficient absorption amount; the surface layer has good dryness, high comfort andexcellent antibacterial deodorizing performance.