Thermoluminescence (TL) measurements are performed to evaluate the trap states in Tl2In2S3Se layered single crystals. TL experiments are conducted with varying temperature from 10 to 300 K and warming rates from 0.2 to 1.0 K s(-1). From the analysis of both initial rise and curve fitting methods, the activation energy of the traps is obtained as 23 meV. The Chen's method is also used to find activation energy. By means of this technique, the activation energy of the TL glow curve is calculated as 25 meV. From both Chen's method and curve fitting method, the existence of mixed order of kinetics in Tl2In2S3Se crystal is found. The cross section to capture of the trap center is found out from the results of curve fitting method. The trap distribution of the crystals is investigated with different temperatures of illumination at a constant warming rate of 0.8 K s(-1). The temperatures of illumination change from 10 to 22 K. As a result of the increase in temperatures of illumination, the peak maximum values move to higher temperatures and intensity of the TL curves decreases. This behavior shows us that quasicontinuous traps distribution is present in Tl2In2S3Se layered single crystals.