The basic theory and design method of a broad-band spatial heterodyne interferometric spectrometer was researched based on the multi-order diffraction of echelle grating. The characteristics of the heterodyne interferometric spectrometer was described and the relationships between the instrument performance parameters (such as spectral resolution, spectral range, signal-to-noise ratio, field of view, and diffraction order) and the initial optical and electronic parameters (such as echelle grating, field prism, imaging system and detector) were discussed. Then, an experimental platform for the broad-band spatial heterodyne spectrometer was settled to demonstrate the above discussions. The designed spectral resolution is 0.173 cm-1@16 950 cm-1, and the spectral range is 500 nm to 700 nm. The broad-band results were given with a laser source (543.5 nm, 632.8 nm), a sodium lamb (589 nm, 589.6 nm) and a mercury lamb (576.96 nm、579.07 nm). It shows that the average wavenumber sampling interval of recovered spectra is 0.17 cm-1.When the triangle apodization is used in the process of spectral recovery, the measured spectral resolution is 0.39 cm-1.The obtained results conform to theoretical results and the relationship among orders of recovered spectrum accords with the theory results decided by grating function.