In this paper, the effect of inlet pressure on the performance of vortex tube device has been investigated using 3D simulation and CFD technique by Fluent software. The flow inside the device is considered as compressible and turbulent. In order to understand and investigate the effect of inlet pressure, different inlet pressures are entered into the device and the results are extracted and analyzed. The main goal is to achieve the minimum cold exit temperature and maximum swirl velocity in the vortex tube. This paper indicates that inlet pressure of 4.8 bars is an optimal inlet pressure which is justifiable economically and also in terms of the amount of produced cooling. The CFD results show that increase in inlet pressure, increases the entropy production and subsequently the system disorder. Finally, the existing gaps in the previous studies will be filled by examining the inlet and exit exergies in the vortex tube device. Inlet exergy has not considerable changes in terms of α and have a constant value and at α=0.3691 the minimum exergy efficiency is occurred according to the calculations.