The invention relates to high-aluminum plastic refractory and a preparation method thereof. The preparation method is characterized by comprising the steps: putting sodium polyacrylate, polyethylene glycol 400, polyacrylamide and water into a container under a water bath condition and stirring to obtain a binding agent; mixing and grinding bauxite, gamma-aluminum oxide micro powder and yttrium oxide micro powder to a particle size smaller than or equal to 80mu m, compression moulding, thermally treating under a condition of 1400 to 1600 DEG C and breaking, grinding and sieving the thermally-treated materials to obtain a material A with a particle size of 3 to 5mm, a material B with a particle size of 1 to 2mm, a material C with a particle size of 0.088 to 0.5mm and a material D with a particle size smaller than 80mu m; mixing the material A, the material B, the material C, the material D and rho-aluminum oxide micro powder to obtain a mixed homogenized material; then adding alumina sol and the binding agent into the mixed homogenized material, mixing and ageing to obtain the high-aluminum plastic refractory. The high-aluminum plastic refractory disclosed by the invention has the characteristics of low cost and simple technology. The prepared high-aluminum plastic refractory has a long retention cycle, a large volume density and high compression strength.