Abstract: In order to measure 3-D profile of a sample with high accuracy, wavenumber-scanning interferometry was used. An optical wedge was used as reference terminal of a Michelson interferometer system. The phases of wedge interference image were extracted by 2-D Fourier transform. The changes of output wavenumber were detected on line. Finally, all the time-resolved interferometry image sequences were sampled by Fourier transform random. The 3-D contour of object surface was restored with high precision. The profile of a sample object was constructed with the resolution of 6.7nm. The proposed method is particularly suitable for quality inspection of mechanical parts.