Abstract: In this paper,experiments and comparison analysis are used to check the reason why casting defect founding rate of High Pressure Turbine blades is higher than ever during the Fluorescent Penetrant Inspection after commissioning of High pressure turbine.The blade′s pre-cleaning methods of Fluorescent Penetrant Inspection are changed and vacuum heat-treating operation is added before Fluorescent Penetrant Inspection and inspection process of Fluorescent Penetrant Inspection is optimized.Experiment proved that the inspection reliability can be improved and the defect rate found in the casting can be decreased.