The invention relates to a CA6-MA-Cr2O3-Al2O3 ladle lining castable and a preparation method thereof. According to the technical scheme, 65-75wt% of CA6-MA-Cr2O3-Al2O3 particles, 5-8wt% of alpha-Al2O3micro powder, 3-6wt% of calcium aluminate cement, 7-10wt% of magnesium aluminate spinel fine powder and 8-12wt% of platy corundum fine powder are taken as raw materials, a polycarboxylate water reducing agent and water are added, and stirring, forming, demoulding and baking are carried out to prepare the CA6-MA-Cr2O3-Al2O3 ladle lining castable. The preparation method of the CA6-MA-Cr2O3-Al2O3 particles comprises the following steps of: mixing 60-70wt% of CA6, 4-8wt% of chromium oxide, 10-20wt% of MA and 10-15wt% of aluminum oxide, and ball milling, adding water, granulating, drying, calcining at 1650-1750 DEG C, crushing and screening to obtain the CA6-MA-Cr2O3-Al2O3 particles with three particle size levels respectively. The product prepared by the method has the advantages of high strength, low thermal conductivity, good thermal shock stability, excellent erosion resistance, energy conservation and environmental protection.