The utility model discloses a polycrystalline silicon ingot casting device which can achieve the purpose of rapid and efficient monitoring. The device comprises a furnace body, wherein a lower supporting heat-insulated board and a heat-insulated cover are arranged in the furnace body; the heat-insulated cover and the lower supporting heat-insulated board form an heat-insulated cage; the heat-insulated cover is connected with a lifting rod; a crucible, a crucible protective plate, a graphite bottom plate, a graphite cover plate, a side heater, a top heater and a heat exchange platform are arranged in the insulation heat insulation cage; an overflow blanket is installed at the bottom of the furnace body; an overflow wire is installed on the upper surface of the overflow blanket; a plurality of overflow holes are formed in the lower supporting insulation board; after silicon fluid flows to the lower supporting insulation board, the silicon fluid can directly flow to the overflow blanket below the overflow hole from the overflow hole, and further burns out the overflow wire arranged on the overflow blanket, so that alarm signals are sent to warn operating personnel to perform relevant operation, and the purpose of rapid and efficient monitoring is achieved. The device is applied to the popularization and application in the field of polycrystalline production equipment.