The invention discloses a high-fluidity polyamide magnetic composite material, prepared from the following ingredients in percentage by weight: 4.3-12.2wt% of polyamide resin, 85-93wt% of strontium ferrite, 0.5-1wt% of an internal lubricant, 1-3wt% of a flow modifier, 0-0.2wt% of an external lubricant, 0-0.1wt% of a primary antioxygen, 0-0.1wt% of an auxiliary antioxygen and 0.3-0.8wt% of a coupling agent. A a sa a preparation method comprises the following steps: (1) mixing the strontium ferrite with the coupling agent, then adding the polyamide resin, the internal lubricant, the flow modifier, the external lubricant, the primary antioxygen and the auxiliary antioxygen, and mixing to obtain a mixture; (2) adding the mixture through a main feeding hole of a double-screw extruder, mixing uniformly, then extruding, and granulating by virtue of a granulator, thereby obtaining the high-fluidity polyamide magnetic composite material.