High-frequency power electronic switching devices generate significant high-frequency magnetic fields in their surrounding space. High-frequency magnetic field energy harvesting devices offer higher output power density, allowing for smaller energy harvesting device volumes and portable installations, compared with grid frequency energy harvesters. Currently, research on the energy harvesting of high-frequency magnetic fields is relatively limited. The establishment of an accurate equivalent circuit model for high-frequency magnetic energy harvesters remains incomplete. Existing transformer models and inductance models are not entirely applicable. Calculating the AC coil resistance caused by skin effect and proximity effect, as well as the additional losses generated by eddy currents within the magnetic core, parasitic capacitance, and AC inductance parameters are highly related with the actual structure and design of the harvester. This paper designs a rectangular magnetic core structure and analyzes the equivalent circuit for high-frequency energy harvesting. Experimental parameter extraction is conducted to validate the correctness of the equivalent circuit model, demonstrating its effectiveness and accuracy.