The invention relates to spinel castables for a coal water slurry gasification furnace and a using method thereof. The spinel castables comprise, by weight, 55-72% of magnesium aluminate spinel particles, 0-15% of tabular corundum particles, 4-10% of magnesium aluminate spinel fine powder, 2-5% of magnesium aluminate spinel micro powder, 4-6% of alpha-Al2O3 micro powder, 0.5-1.5% of Y2O3 micro powder, 0.5-1.5% of CeO2 micro powder, 0.2-1% of TiO2 micro powder, 1-7% of pure calcium aluminate cement, 2-12% of CMA cement, 0.03-0.1% anti-explosion fibers, and 0.1-0.3% of FS series water reducer. The using method comprises the steps of pouring water which accounts for 4.8-6.2%, by weight, of the castables in the castables, stirring evenly, and carrying out forming, conservation, demoulding and baking. Products prepared through the spinel castables for the coal water slurry gasification furnace have the advantages of being environmentally friendly, good in coal slag permeation resistance and anti-corrosion performance, capable of saving energy, high in strength and good in thermal shock stability, and thus demands of the production of the coal water slurry gasification furnace are met.