Abstract: An impeller disk of the fan part of a compressor failed during testing. Based on macro and micro appearance observation, metallurgical structure inspection, mechanical property testing, fatigue simulation test, and verification for improved methods, the failure mechanism and cause were found. The results showed that blade fractured firstly, which happened in a high cycle fatigue mode. Drum and disk fractured in an over-loading mode. The transversal machining marks on surface of fractured blade, inferior microstructure and low fracture toughness were the cause of high cycle fatigue fracture. The mechanical property of the forging blank was improved, and the surface quality was strictly controlled. As a result, the failure of the impeller disk was effectively prevented.