Abstract: The probability-of-detection curves can be used to evaluate the capability of a crack detection method, and it is also the foundation for aircraft manufacturers to establish structure maintenance program. The efficient estimation of POD curves for fatigue crack is significant to the safety of aeronautical structures. Based on the theory of reliability, the number of experimental points, the crack sizes of each specimen, and the minimum detection number are studied in this paper. The procedure for estimation of the POD curves which describe the reliability of detection is also presented.