The invention relates to a silicon dioxide-based anti-adhesion agent used for a polyolefin thin film and a preparation method thereof. The silicon dioxide-based anti-adhesion agent is suitable for plastic thin film production enterprises. The preparation method includes the following steps of: 1) preparing silicon dioxide sol from tetraethyl orthosilicate under alkaline conditions; 2) adding a surfactant and a proper oil phase organic substance, and stirring the mixture to prepare a micelle with silicon dioxide as a shell layer; 3) adding trimethoxy silane containing an R group and a catalyst to the micelle with the silicon dioxide as the shell layer, and stirring the mixture to prepare silicon dioxide-based microspheres at a certain temperature, wherein the surfaces of silicon dioxide are modified by silane; and 4) drying the microspheres to remove the oil phase to obtain silicon dioxide hollow microspheres. The silicon dioxide-based anti-adhesion agent is a compound having definite structural and molecular formulas and molecular weight, but is a hollow microsphere which has a hierarchical pore structure and is based on silicon dioxide. The anti-adhesion agent can reinforce a plastic thin film and improves creep resistance, wherein a large quantity of micro projections and gaps are formed on the surface of the thin film, thereby increasing roughness of the thin film, reducing friction coefficient and preventing adhesion of the thin films.