In a wide range of electrical applications, an accurate measurement of the high-frequency current signal is urgently required. Owing to inherent superiorities, iron-core coils have been widely applied to the measurement of high-frequency current signals. Nevertheless, the uneven winding, bandwidth-sensitivity exclusion, and partial resonances have restrict better high-frequency characteristics. To address the issues, an optimization design is proposed in this paper, and it includes three key improvements: the Core-PCB hybrid structure, staggered secondary winding, and distributed sampling resistances, which respectively contribute to better uniformity of winding, smaller stray capacitances, and effective suppression on partial resonances. Moreover, simulations and tests are conducted, and the results verify the validity.