The invention discloses a method for preparing high-permeability flaky soft magnetic alloy powder. The method is characterized by comprising the first step of raw material selection, wherein soft magnetic alloy magnetic powder which can be used as an absorbing agent is selected, features are not limited, and a solvent is selected; the second step of primary ball milling; the third step of primary reduction treatment; the fourth step of secondary ball milling; the fifth step of grading, wherein size grading is conducted on magnetic powder in the fourth step through an airflow grading technology, and magnetic powder with the radius-thickness ratio smaller than 50: 1, magnetic powder with the radius-thickness ratio ranging from 50: 1 to 100: 1 and magnetic powder with the radius-thickness ratio larger than 100: 1 are screened out; the sixth step of secondary reduction annealing treatment; and the seventh step of decentralized treatment. The method has the advantages that the manufacturing technology is simple, the manufacturing cost is low, the finished product rate is high, the radius-thickness ratio is large, and the permeability is high.