The thermal barrier coating of aviation turbine blades can reduce the surface temperature of the blades and prevent high temperature corrosion on the surface. The coating defects affect the performance of the blades seriously. The complex blade surface shape and its matrix structure lead to the difficulty of non-destructive testing of coating defects. In view of the sensitivity of Rayleigh wave to damage changes such as surface stress and surface micro-cracks, a non-destructive testing method for micro-crack defects on the surface of turbine blade thermal barrier coating based on generalized Rayleigh wave propagation is proposed. A special ultrasonic array transducer was designed and a Rayleigh wave detection system was built. The Rayleigh wave detection signal propagating in the back coating along the width direction of the blade was extracted, and the correlation between the distribution characteristics of the blade amplitude and the complex structure inside the blade was analyzed. Finally, the influence of artificial narrow slots in the blade on the propagation characteristics of Rayleigh waves is analyzed, and a generalized Rayleigh wave detection method for coating defects is proposed. The results show that the complex surface profile and the inner cavity diversion structure of the turbine blade have a significant effect on the amplitude of the Rayleigh wave. The Rayleigh wave amplitude distribution of the intact blade coating is compared with the Rayleigh wave amplitude distribution characteristics of the blade coating with a narrow groove (500 μm×80 μm×20 μm). The results show that the ultrasonic amplitude propagating on the path with a narrow groove increases significantly, with an average increase of 54.3 mV. This feature can be used for non-destructive testing of micro-crack defect damage on the surface of turbine blade thermal barrier coating.