Absorption Spectra and Photoluminescence (PL) spectra of CsI∶Tl crystals with various Tl+-concentrations were measured for absorption and luminescent research in CsI∶Tl. Their UV absorption spectra contained three peaks at 297, 273 and 247 nm. The experiments were demonstrated that the peaks in the high Tl+-concentration CsI∶Tl crystals are broader than ones in the low Tl+-concentration crystals and their absorption A-peak shift by 20 nm, but their PL with UV excitations are similar. It was suggested that lattice distortions in the high Tl+-concentration CsI∶Tl lead to the changes in absorption or fluorescence excitation peaks, but no changes in the fluorescence band widths and locations at room temperature.