The photoluminescence measurements of alkaline metal doped zincselenide (ZnSe) single crystals were carried out to investigate how the impurity atoms substitute the intrinsic vacancy. Sample are grown by the sublimation method and the Li and Na with the concentrations of 0.1, 0.25 and 0.5 mol% were incorporated simultaneously. In the PL spectra with lower impurity concentrations, bound exciton lines of deep acceptor and donor-acceptor pair (DAP) bands were clearly observed accompanied by a weak free exciton line. Although the bound exciton lines becomes smaller with increasing the impurity concentration, the DAP band remains strong and its peak energy shift to lower energy side with the concentration. The decrease of the bound exciton lines is drastic for Li-doped sample than Na-doped sample. This indicates that Li atoms more easily occupy the Zn vacancies than Na.