Eddy currents oecur when the AC current flows through the RLC resonant cireuit, and the coiresistance will rise sharply as the AC frequency increases. Because the mechanism of skin and proximity effectsbetween single-core coils and multi-core coils is different ,the AC resistance of the two coils is diflerent with theinerease of AC frequeney.T'he relationship between resistance and AC frequency in single-core and multi-corewires was measured by the resonance method, and the eddy current losses of single-core and multi-core coilsunder difflerent AC frequencies were simulated and calculated , which showed that in the case of high-requency AC , the eddy current elfect of multi-core coils was higher than that of single-core coils,Experimental tests are inagreement with the calculated results.