Reliability analysis is a key means to quantitatively evaluate the effectiveness of nondestructive test technology. In order to solve the problem that EDM grooves can not effectively characterize fatigue cracks in real components, a transfer function method based on response signal is proposed. Firstly, this paper adopts eddy current detection method to quantitatively obtain the signals of manual grooving defects and fatigue crack defects of the flat plate test block and the signals of manual grooving defects of the target turbine disk test block. Then, according to the curve signals, the transfer function between the eddy current detection data of manual grooving defects and fatigue crack defects of the aero-engine wheel plate sample is established. The probability of detection (POD) curve of aero-engine wheel fatigue crack is obtained. The results show that: Under the condition that the real sample could not be obtained, this paper established the transfer function between grooving and fatigue crack by empirical method, and calculated that the fatigue crack defect of aero-engine wheel that can be effectively detected by eddy current testing is 1.88 mm×0.94 mm, which provides a basis for the design of aero-engine wheel damage tolerance and maintenance planning. It has important guiding significance to the application reliability research of nondestructive testing methods.