The effect of a high magnetic field up to 30T on phase transformation temperature and microstructure of Fe-based alloys has been reviewed. A high magnetic field accelerates ferrite transformation, changes the morphology of the transformed microstructures and increases the A_3 and A_1 temperature. In a magnetic field of 30T, the A_1 temperature increases by about 37.1℃ for Fe-0.8C, the A_3 temperature for pure Fe increases by about 33.1℃. The measured transformation temperature data are not consistent with calculation results using Weiss molecular field theory. Ferrite grains are elongated and aligned along the direction of magnetic field in Fe-0.4C and Fe-0.6C alloys by ferrite transformation, but elongated and aligned structure was not found in pure Fe, Fe-0.05C alloy and Fe-1.5Mn-0.11C-0.1V alloy. The effect of a high magnetic field up to 30T on phase transformation temperature and microstructure of Fe-based alloys has been reviewed. A high magnetic field accelerates ferrite transformation, changes the morphology of the transformed microstructures and increases the A_3 and A_1 temperature. The A 1 temperature increase by about 37.1 ° C. for Fe-0.8 C, the A 3 temperature for pure Fe increases by about 33.1 ° C. The measured transformation temperature data are not consistent with the calculation results using Weiss molecular field theory. Ferrite grains are elongated and aligned along the direction of magnetic field in Fe-0.4C and Fe-0.6C alloys by ferrite transformation, but elongated and aligned structure was not found in pure Fe, Fe-0.05C alloy and Fe -1.5Mn-0.11C-0.1V alloy.