Infrared (IR) thermal wave inspection is a merging technology in nondestructive evaluation. Different from conventional passive infrared inspection, infrared thermal wave inspection work with a sample under transient or alternating temperature field. The surface temperature is recorded by a infrared camera, and the data collected are processed according to the type of the temperature field and correspond physical model. Using lock-in thermography to test fiber reinforced plastics (FRP) material by SC3000 IR camera, and calculated by the fast Fourier transform (FFT) algorithm. Results show that the phase diagram effect is better than that of amplitude diagram, and different loading frequencies have different experimental results.