The optical properties of (1−x)Ba 0.75 Al 11 O 17.25 –xBaMgAl 10 O 17 solid solutions doped with Mn 2+ have been evaluated using VUV excitation and emission spectroscopy. A band at 178nm is improved with the increase of x and assigned to the absorption of the mirror layers of Ba 0.75 Al 11 O 17.25 and BaMgAl 10 O 17 . The excitation of spinel blocks in Ba 0.75 Al 11 O 17.25 and BaMgAl 10 O 17 is found at a wavelength shorter than 160nm and further assignments have been made: the AlO 4 5− cluster's absorption band could appear near 133nm, the MgO 4 6− cluster's at 160nm and AlO 6 9− cluster's at between the former two bands. The optimum emission intensity is about x=0.2. It is concluded that the photoluminescence properties of Ba 0.75 Al 11 O 17.25 :Mn 2+ or BaMgAl 10 O 17 :Mn 2+ can be improved by Ba 0.75 Al 11 O 17.25 –BaMgAl 10 O 17 solid solution with appropriate composition.