To meet the requirements of compactness and miniaturization for double-pulse test platforms, this paper proposes a design of a toroidal air-core reactor to address the severe magnetic field leakage issue associated with traditional solenoid and dry-type air-core reactors. The reactor is wound with Litz wire and optimized based on the equivalent current loop theory. The inductance value and parasitic parameters of the reactor are calculated through theoretical analysis and electromagnetic field simulation software such as Ansys, and its insulation performance, thermal stability, and dynamic stability are verified. Based on its dual-layer winding configuration, the reactor offers three selectable values to accommodate diverse testing scenarios. The results show that the toroidal air-core reactor has high energy storage density, low magnetic field leakage, and good stability, with its energy storage density being 28.389 times higher than that of traditional solenoid reactors. The reactor performs well in double-pulse testing. The conclusion indicates that the proposed reactor design meets the developmental requirements of double-pulse test platforms and can serve as an important technical means for their compact and miniaturized development.