The invention discloses a cross-scale surface topography measurement device and method based on optical phase shift. The device comprises a computer, a light intensity controllable white light source, a first lens, a filter rotating disk, a beam splitting prism, a second lens, a third lens, a CCD (Charge Coupled Device) camera, a spatial light modulator (SLM) and a fourth lens. Accurate optical phase shift is realized by the pure phase modulation type liquid crystal SLM, four kinds of monochromatic light having consistent light intensity distribution are obtained by the light intensity adjustable white light source and four band pass filters, and the measurement range is expanded via reasonable size engagement by using the principle of multi-wavelength interference. In repeated optical phase shift, interferential image series of different wavelengths are acquired in a manner of alternating the filters, and point-by-point and frame-by-frame phase operation is performed by using an optimized four-step phase shift method to obtain the height of a topography point within a large scale range. The device and the method can meet the requirement of cross-scale measurement range and keep the nano precision of single-wavelength interference, and have important application value.