The invention is suitable for the field of optics, and provides a splicing display device and a splicing display control method. The splicing display device comprises at least one projection display unit and a splicing control unit, wherein each projection display unit comprises an excitation light source, a compensation light source and a color wheel assembly for sequentially emitting at least one excited light beam under irradiation of the excitation light source; compensation light and the at least one excited light beam are simultaneously emitted, have overlapped spectra and can be mutually adjusted independently; the splicing control unit comprises a color coordinate adjustment module which is used for adjusting color coordinates of first primary color light of various projection display units through modulating the compensation light sources and the excitation light sources in the projection display units separately, so that the color coordinates of the first primary color light of the projection display units are consistent. By the splicing display device and the splicing display control method, the loss of a color gamut range is reduced while the consistency of the color coordinates of the primary color light of the projection display units is ensured.