Spectrally resolved interferometry is widely used in the measurement of distance, displacement, film thickness, and surface morphology in micro/nano-scale geometric measurement. The core of spectrally resolved white-light interferometry is phase extraction. Temporal phase shifting, Fourier transform, wavelet transform, and other methods are commonly used in phase extraction of spectrally resolved interferometry. The S-transform, providing frequency-dependent resolution and having good time-frequency characteristics, is widely used in power quality disturbance analysis, seismic wave analysis, and phase recovery in profilometry. S-transform is used to extract the phase of the spectrally resolved white-light interferometry signal measuring step height. Compared with Fourier transform and wavelet transform, it is proved that S-transform is a feasible method in phase extraction of spectrally resolved interferometry measuring step height.