The invention discloses an alumina bubble lightweight insulating refractory casting material, which comprises the following components in percentage by weight: 10 to 50 percent of alumina bubbles, 5 to 15 percent of mullite with the grain diameter of 5 to 3 millimeters, 5 to 20 percent of mullite with the grain diameter of 1 to 3 millimeters, 10 to 20 percent of mullite with the grain diameter of 0 to 1 millimeter, 1 to 13 percent of swelling agent, 10 to 25 percent of fine powder, 10 to 20 percent of micro powder, 0.1 to 1 percent of water reducing agent and 5 to 20 percent of composite aluminate cement. The casting material has the characteristics of carrier weight reduction, high temperature resistance, good heat insulation effect, large strength, convenient and practical operation, and suitability for being used at the temperature of between 1,000 and 2,000, can be used for integrally casting, spraying, coating and repairing, and not only meet the requirement of smelting special steel, but also meet the requirements of refractory materials for hot-blast stoves, furnace tops, furnace walls, petrochemical cracking furnaces, systems for chlorine and sulfur removal, slag discharge and catalytic cracking, electric fluidized bed boilers, flues and the like.