White light interferometry for topography measurement can avoid phase uncertainty trouble which exists in laser interferometry. Spatial Frequency Domain Algorithm (FDA), based on white-light scan interferometry, has the advantage of insensitivity to noise and higher calculation accuracy compared with other methods. Applying FDA, two white light scanning tests on the surface of a step-like sample are carried on with a Mirau typed scan interference microscope. Thus two stepped profile results are obtained, their step heights difference not exceeding 1 nm. Meantime, the same sample is also tested with a Zygo Newview 7200 profiler, both topography results agreeing with each other and step heights differing by 0.9 nm. Besides, data processing results also show that the chromatic dispersion higher than 2nd order is completely negligible when applying FDA.