In this research, high entropy nanostructured alloy 𝐹𝑒40𝐶𝑜20𝑁𝑖20𝑉10𝐶𝑢10 was synthesized by mechanical alloying method. The structural characterizations were performed by x-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive x- ray spectroscopy (EDX) while magnetic and thermal characterizations were implemented by vibrating sample magnetometer (VSM) and differential scanning calorimetry (DSC) respectively. After 110- h of milling time, XRD analysis showed the formation of solid solution phase of (Fe-Ni) with FCC structure that was consistent with thermodynamic predictions. The lowest crystallite size and highest lattice strain were observed for samples milled for 48 and 110-h with values of 14 nm and %66 respectively. The saturation magnetization showed a decreasing trend from the beginning of the milling process, whereas the coercivity showed an increasing trend with a gentle slope. The heat treatment at 480 ° C for the 110-h sample leaded to increase of crystallite size, coercivity and saturation magnetization, whereas the annealing to 800 ° C caused the grains to grow more and therefore reduced the coercivity and