Disclosed is a method for preparing a water-absorbent polymer composite comprising the steps of contacting a droplet containing a solvent and said polymerizable monomer before polymerization and/or under polymerization with first fibers fed through a first supply port of said reactor in a gas phase, proceeding with polymerization of said polymerizable monomer, contacting the resultant droplet containing said solvent, the polymerizable monomer under polymerization and said first fibers with second fibers fed through a second supply port of said reactor in a gas phase, and proceeding with further polymerization of said polymerizable monomer to form said water-absorbent polymer composite. The water-absorbent polymer composite prepared by the method is characterized in that the fibers are stably fixed to the water-absorbent polymer not only in dry but also in wet through water absorption for swelling, the water-absorbent polymer content can be enlarged relative to the fibers, the polymer can be uniformly fixed to the fibers, the composite is flexible and can be thinned, and it can be opened by itself and can be uniformly mixed with any other material.