The invention relates to a hydrogel patch and a preparation method thereof. The hydrogel patch consists of three parts: bidirectional flexible non-woven fabric, medicament-containing paste and a cover film layer, wherein the main part, namely the medicament-containing paste is prepared from fluid extract and proper hydrogel matrixes such as an adhesive, a humectant, an excipient, a pH modifying agent, a cross-linking agent, a transdermal enhancer, a filler, a dispersant, a chelating agent, a tackifier and deionized water according to a proportion, wherein the tackifier is at least one of polyvinyl alcohol, povidone, gelatin, carboxymethyl cellulose, collagen, modified starch and plant polysaccharide, or is emulsion formed by polymerizing free radicals of 0-30 percent acrylic acid, 0 to 50 percent vinyl pyrrolidone and 0 to 50 percent 2-acrylamido-2-methylpropanesulfonic acid, and is added in an amount which is 5 to 15 percent based on the total weight. The hydrogel patch solves the common problem of poor viscosity of common hydrogel, and has the characteristics of high adhesion, high compliance with skin, quick response, reusability, moisture retention, permeability and comfortable use.