In order to solve the shortcomings of the narrow range of operating conditions and constrained application scenarios in existing magnetic component parameter design methods, this paper introduces a novel magnetic component parameter design method for dual active bridge (DAB) converters. This approach is based on variable load conditions, expanding its applicability. Moreover, the proposed magnetic component design method incorporates an optimal modulation strategy to minimize current stress and extend the soft-switching range under predefined operating conditions, thus improving the efficiency. Firstly, the objectives of the design method are established, and the critical factors affecting the current stress and soft switching are analyzed. Secondly, an optimal modulation strategy aiming to minimize current stress with zero-voltage-switching (ZVS) or quasi-zero-voltage-switching (QZVS) is selected. Thirdly, the optimization method of magnetic component parameters is analyzed under variable load conditions. Finally, the design process of the optimal magnetic component parameters is summarized in the form of a flowchart. A 1-kW experimental platform was built to validate the effectiveness and superiority of the proposed method.