The invention provides a preparation method of a comb type high-molecular sand fixation and water retaining agent, comprising the following steps of: firstly, adding alkyl vinyl polyglycol ether, tetraethyl orthosilicate and catalyst p-toluenesulfonic acid into a reaction vessel, at the temperature of 50-150 DEG C, reacting for 2-10 hours, removing the solvent by vacuum evaporation to get the macromonomer; then, mixing vinyl acetate, butyl acrylate and acrylamide to get the polymerized small monomer; and finally, adding the macromonomer into the reaction vessel, adding the polymerized small monomer, water and emulsifying agent, heating up to 60-80 DEG C, dropping 40-100 parts of 5% ammonium persulfate water solution, finishing dropping within 180 minutes, preserving heat for reaction for 180-240 minutes, cooling, and obtaining the comb type high-molecular sand fixation and water retaining agent. For the comb type high-molecular sand fixation and water retaining agent, the production technology is clean and environment-friendly, and the production process is simple and convenient; the prepared comb type high-molecular sand fixation and water retaining agent forms cross-linked network with the sandy soil, and can realize higher sand fixation strength with low dosage; and the comb type high-molecular sand fixation and water retaining agent is high in strength and excellent in durability.