Iron-based amorphous alloys have received a considerable attraction because of their excellent soft magnetic properties (high magnetic permeability, high electrical resistance and low coercivity), good mechanical properties while having low cost. The most important challenge in Iron-based amorphous alloys, is the low amorphization forming ability. The aim of this research was to investigation of development of amorphous forming ability with a special consideration in magnetic properties. Some elements such as Cobalt, Titanium, Aluminum, Silicon, Boron, Phosphorous and Carbon seem to be good elements to be added to Iron-based alloys for successful amorphisation in mechanical alloying (MA) technique with respect to thermodynamics, kinetics and magnetic requirements. In this research, three alloy systems designed and thermodynamic analysis for prediction of amorphous forming ability have investigated.. Prediction based on extended Miedema model in Fe 70 Co 7 Si 8 B 8 P 7 (alloy I), (Fe 65 Co 35 ) 70 Ti 15 Al 5 Si 3 B 3 P 2 C 2 (alloy II) and (Fe 50 Ti 25 Al 25 ) 70 B 15 P 7 C 6 Si 2 (alloy III) showed that Gi free energy changes for solid state amorphisation were -181, -308 and -451 (kJ mol -1 ) respectively, and thermodynamic analysis showed the (Fe 50 Ti 25 Al 25 ) 70 B 15 P 7 C 6 Si 2 (alloy III) has more thermodynamic driving force for amorphous phase formation. MA experiments in three different alloy systems showed that the most amorphous forming ability is related for (Fe 50 Ti 25 Al 25 ) 70 B 15 P 7 C 6 Si 2 (alloy III) with amorphous-nanocrystalline final structure that is according to thermodynamic prediction. Adding 20 at. % Cobalt to (Fe 50 Ti 25 Al 25 ) 70 B 15 P 7 C 6 Si 2 (alloy III), showed improve amorphous forming ability and compeletely amorphous structure have achieved . Magnetic properties of (Fe 50 Ti 25 Al 25 ) 70 B 15 P 7 C 6 Si 2 (alloy III) and (Fe 50 Ti 25 Al 25 ) 70 B 15 P 7 C 6 Si 2 – Co 20 was investigated, too. In (Fe 50 Ti 25 Al 25 ) 70 B 15 P 7 C 6 Si 2 (alloy III), magnetic saturation and coercivity field were 30 emu/g and 125 Oe respectively. However, adding 20 at. % Cobalt ((Fe 50 Ti 25 Al 25 ) 70 B 15 P 7 C 6 Si 2 – Co 20 ) showed improvement on magnetic saturation to 82 emu/g and increased coercivity field to 128 Oe. Also, the squareness ratio ( Mr / Ms ) was decreased. In this research, adding Cobalt to (Fe 50 Ti 25 Al 25 ) 70 B 15 P 7 C 6 Si 2 (alloy III) alloy system, improve amorphous forming ability and soft magnetic properties. Key words: Amorphous – Nanocrystalline materials, Iron-based amorphous allos, Mechanical alloying, Magnetic properties.