Abstract: The fatigue failure is an important factor to damage compressor crankshaft. There is a lack of effective early diagnosis method for the failure mode for long a time. The tensile and fatigue progress tests are carried out for nodular cast iron, which is the common materials of the compressor crankshaft, and the fatigue life is simulated by the finite element. Magnetic indicator of stress concentration (TSC1M4) is used to record and analyze characterization of magnetic memory signal throughout the whole test. The results show that magnetic memory testing technology can effectively determine the various stages of fatigue failure of nodular cast iron. This technique can be applied to evaluate the inservice compressor crankshaft.