The invention relates to a filtering device for increasing the purity of nickel-based superalloy powder. By arranging a fixed combined filter in a casting tundish, the filtering device achieves the objective of purifying superalloy melt and stabilizing melt flow, consequently, various nonmetallic impurities in the superalloy powder are effectively reduced, the purity of powdery superalloy disks is improved, the safety reliability of powdery superalloy turbine disks and other hot end parts of engines are enhanced, and the service lives of the powdery superalloy turbine disks and the other hot end parts of the engines are prolonged.