The invention discloses a high-dispersion and stable-suspension superfine yttrium oxide glue-containing sizing agent and a preparation method thereof. The superfine yttrium oxide glue-containing sizing agent is characterized by being prepared from superfine yttrium oxide powder of which the mass is 5 to 15 percent (by mass) of that of the sizing agent and the rest of an alkaline glue-containing alcohol and water mixed solution. The alkaline glue-containing alcohol and water mixed solution is prepared from water, ethyl alcohol, sodium hydroxide and a polyvinyl alcohol glue solution (commonly known as liquid glue), a PH (Potential of Hydrogen) value is equal to 10 best, wherein the volume of the polyvinyl alcohol glue solution is 3 to 5 percent (by volume) of that of the alkaline glue-containing alcohol and water mixed solution, and the rest is an alcohol and water mixed solution of which the volume ratio of the ethyl alcohol to the water is 2: 3. The sizing agent is coated on a surface of a material to-be-modified, a superfine yttrium oxide particle pre-coated layer which is strong in adhesivity and further dispersive in distribution can be formed on the surface of the material to-be-modified after the sizing agent is dried and cured, and the demand of introducing superfine powder into the field of particle surface modification techniques of laser melt injection and the like can be met.