The current study presents numerical investigation of the vortex tube performance. ANSYS-15 software and its' tools are used to simulate the flow through vortex tube. The basic governing equations of mass, momentum and energy conservation in addition turbulence equations are used to predict the flow along vortex tube. 3-D, compressible and turbulent flow with certain boundary conditions are applied to calculate the flow parameters. Comparisons between published experimental data and present numerical results are performed to select the suitable turbulence model and to valid the numerical model. The validation appeared that standard (k-ε) is the best turbulence model based on the calculated coefficient of correlation. The effect of operating conditions (inlet pressure, cold mass fraction 〖m^.〗_cf and geometric parameters of vortex tube such as number of inlet nozzles, hot tube length and diameter with constant ratio 𝐷𝑐/𝐷ℎ on vortex tube performance are studied. The numerical results show that, the maximum values of cooling and heating coefficient of performance is achieved at lowering inlet pressure. The hot and cold temperature differences increase with increasing inlet pressure. The maximum cold temperature difference can be obtained at 〖m^.〗_cf between 0.22 and 0.36 when the inlet pressure changes from 1.0 to 5.0 bar. The hot temperature difference increases with increasing 〖m^.〗_cf for all studied inlet pressures. The numerical results indicated that the highest value of cold and hot temperature differences achieved at hot tube diameter, hot tube length (Lh) and diameter ratio 𝐷𝑐/ 𝐷ℎ of 1.3 cm, 25 cm and 0.5 respectively.