The mechanical properties of steels are influenced by their plastic deformations. In austenitic steels, plastic deformations may occur through different mechanisms including dislocation gliding, twinning and phase transformation. The stacking-fault energy governs the activation of these mechanisms; therefore it is a crucial parameter for understanding the plastic deformations. The aim of this is the investigation of role of temperature and magnetic effects on the stacking-fault energy in austenite Iron and Nickel. Our results demonstrate a strong dependence of the behavior of the magnetic effects in iron and lower dependence of the behavior of the magnetic effects in nickel. Also, when we increase the temperature, the stacking fault energy in iron is increasing and in nickel is decreasing. The SFE is calculated using the axial next-nearest-neighbor Ising (AI) model. The random alloy and the paramagnetic state are taken into account, respectively, using the coherent-potential approximation (CPA) and the disordered local moments (DLM) approach, as implemented in the exact muffin-tin orbitals (EMTO) code. The lattice parameter at different temperatures is provided using the Thermal lattice expansion data measured by X-ray diffraction (XRD). The results demonstrate for the first and second order of model.