The invention discloses a high-strength, high-purity and low-silicon corundum brick for a petrochemical industry. The corundum brick comprises the following components in percentage by weight: 3-6% of 5-3 mm white fused corundum, 15-25% of 3-1 mm white fused corundum, 8-12% of 1-0 mm white fused corundum, 3-8% of 150-mesh white fused corundum, 12-16% of 320-mesh white fused corundum, 15-20% of 3-1 mm tabular corundum, 3-7% of 1-0 mm tabular corundum, 6-11% of 320-mesh tabular corundum, 8-13% of micro alumina powder and 2-5% of rho-Al2O3, wherein the total amount of the components is 100%, and the weight of aluminium collosol accounts for 6-13% of the total weight of the components. The invention further discloses a preparation method for the high-strength, high-purity and low-silicon corundum brick for the petrochemical industry. The high-strength, high-purity and low-silicon corundum brick has the characteristics of being low in firing temperature, low in impurity content, high in strength, and excellent in high-temperature property.