The making of Fe-6.5Si alloy magnetic powder core comprises grain proportion, alloy powder inactivating, adding insulation agent to the metal powder, binder, lubricant and stripping agent, compression, heat treatment, solidification, surface coating, with the inactivating treatment getting phosphopyruvic acid with 5-15% phosphate chrome, the rest being acetone, adding alloy powder with 2-6% of mass percentage. Adding small quantity Ti nor Ni, it can reach the saturated alloy magnetic sensing strength BS value of 16000- 18000 Gaussian, coercitive force <=80A/m. It has better forming and compression feature. It reduces broken stress. The made magnetic powder core having magnetic conductivity of 125, with low metal core consumption.