PURPOSE: A method for predicting the influence of damage to an aircraft caused by corrosion on fatigue is properly predicted by using an equivalent initial flaw size conception and fracture mechanics. CONSTITUTION: A method for predicting the influence of damage to an aircraft caused by corrosion on fatigue includes the following steps of: performing a fatigue test under uni-axial stress by collecting a fatigue sample from an actual component of the aircraft (S101); observing the fraction surface of a fractured testing piece in consequence of the fatigue test by using a scanning electron microscope (S102); comparing and analyzing the depth, the width, and the area of a damaged portion based on EIFS conversion modeling with an equivalent initial flaw size value obtained through an inversion method (S103); and predicting a stress-fatigue lifetime curve under various stress conditions by using the equivalent initial flaw size value obtained by the inversion method (S104); and predicting the stress-fatigue curve under various stress conditions. [Reference numerals] (S101) Performing a fatigue test under uni-axial stress by collecting a fatigue sample from an actual component of the aircraft; (S102) Observing the fraction surface of a fractured testing piece for the fractured testing piece generated from the fatigue test in the S101 step by using a scanning electron microscope (SEM); (S103) Comparing and analyzing the measured values of the depth, the width, and the area of a damaged portion affecting a real crack generating unit, which are observed in the S102 step, based on an equivalent initial flaw size (EIFS) conversion modeling with an EIFS value obtained through an inversion method; (S104) Predicting a stress-fatigue lifetime curve under various stress conditions by using the EIFS value obtained by the inversion method from the stress-fatigue (S-N) curve drawn from the execution of the fatigue test under the stress conditions