Abstract: Stepped frequency pulse signal was applied in microwave nondestructive testing, which was advanced by this paper. Based on scattering center model the theory of stepped frequency pulse testing of weld track was analyzed. The analyzed results manifested this kind of waveform can test weld track. The designing rule of waveform parameters were given out. By simulating the fuzzy ambiguity function of stepped frequency waveform manifested this waveform possessed high range resolution rate, which was the basement of gaining one-dimensional range profile of welding track. Based on the above analysis and designation IFFT profiling algorithm was advanced and its profiling theory was analyzed. The results manifested this algorithm could realize the one-dimensional range profile of welding track. Under the common conditions this algorithm was simulated and the results meant using it could gain the whole one-dimensional range profile of welding track.