The invention relates to a silicon dioxide based light ceramic heat protection material and a preparation method and an application of the material. The heat protection material takes a rigid heat insulation tile as a matrix, and is compounded with Si-O-C aerogel; and the surface of the material is coated with a reinforced coating. The preparation method comprises the steps of preparing the rigid heat insulation tile matrix and an Si-O-C collosol precursor, dipping the rigid heat insulation tile matrix in the Si-O-C collosol precursor, performing aging, solvent replacement and supercritical drying sequentially to form a rigid heat insulation tile based Si-O-C aerogel composite, and applying the surface reinforcement coating on the external surface of the rigid heat insulation tile based Si-O-C aerogel composite to prepare the silicon dioxide based light ceramic heat protection material. The prepared material is low in density and high in compressive strength, further has the characteristics of low ablation velocity, low heat conductivity, high emissivity, good heat insulation effect and excellent air flow scouring resistance and can be used as a heat protection material of the external surface of an outer space exploration vehicle.