Abstract: Taking the fan blades of the thermal power unit generator as the research object, an eddy current experiment is carried out on them. By searching the parameters such as detection frequency, lift-off effect and scanning direction, the suitable detection technology is used to replace the traditional penetration detection. The experimental results show that the effective detection frequency of the fan blades of the thermal power unit generator is between 300-1 400 kHz, which is consistent with the calculated value. The signal reduction caused by the lift-off effect on the fan blade can be compensated by increasing the gain, the scanning direction has no effect on the defect signal strength. Finally, suggestions are therefore made for the array eddy current field test of generator fan blades.