The invention discloses a method for preparing high frequency soft magnetic iron-silicon-aluminum magnetic powder cores, and belongs to the technical field of energy storage materials. Firstly, an iron-silicon-aluminum alloy is crushed by a machine and graded with powder of different particle sizes to prepare graded alloy powder, the graded alloy powder, absolute ethanol, polyvinylpyrrolidone anddopamine are subjected to ultrasound dispersion and reaction under the nitrogen protection to prepare graded alloy powder syrup, then a diluent of ethyl orthosilicate is dropwise added into the gradedgold powder syrup, a catalyst is added after dropwise adding, after stirring and mixing, an ethanol solution is added, a stirring reaction continues, and filtering, washing and drying are then conducted to obtain modified ally powder; the modified alloy powder and an insulating binder are mixed and dried, a release agent is added, injection compression molding is conducted, demolding is conducted, after stabilization treatment and heat treatment, cooling is conducted, and then the high-frequency soft magnetic iron-silicon-aluminum magnetic powder cores are obtained.