The invention relates to organic silica gel for packaging a large-power LED and a preparation method thereof. The gel is prepared by mixing a component A of vinyl-contained polysiloxane, a silicon resin component B, a component C of hydrogen-contained polymethylsiloxane, a platinum catalyst component D, a catalytic inhibiting agent component E and a thickening agent component F, and the obtained packaging gel with different refractive rates of 1.4 grade, 1.5 grade, and the like is used for packaging various types of large-power LEDs or is used as other optical purposes. By adopting the component B as a filling material, the invention solves the problems of temperature resistance, color change, light transmittance and needle penetration reduction of the large-power LED product, can be made into two packaging types of a single component and double components, improves the adaptability on packaging equipment and the manufacture procedure and the efficiency, reduces the cost and is convenient for use.