Abstract: MnZn ferrite U-type magnetic core parts were prepared by multi-physical fields coupling sintering technology(Micro-FAST), and the effects of heating rates on the microstructure and properties of MnZn ferrite cores were investigated.The results show that under the temperature increasing rate of 30 ℃/s, pressure of 75 kg, sintering temperature of 900 ℃and insulation time of 360 s, the sintered core has a density of 4.87 g/cm³, saturation magnetization of 55.78 emu/g, residual magnetism of 1.59 emu/g, coercive force of 14.83 Oe, and resistivity of 3.88 Ω·m.With the increase of heating rate, the density of the magnetic core increases, the pores reduce, the nucleus and growth of the spinel phase grains are promoted, and the microstructure is more even, so that the magnetic properties of the MnZn ferrite magnetic core improve.