Bidirectional DC/DC converters have been widely used in recent years. As the key components of bidirectional DC/DC converters, magnetic components play an important role in their size and performance. In this paper, the inductor of four-phase interleaved parallel DC/DC converter is taken as the research object. The design of coupling inductor is studied, and a magnetic core structure of four-phase coupling inductor is proposed; a mathematical model of the equivalent inductor is derived through theoretical analysis. Under the condition that the dynamic performance remains unchanged before and after coupling, the inductor ripple of each phase is effectively reduced by the inverse-coupled design. Furthermore, the actual customized magnetic components of discrete inductor and coupling inductor are fabricated respectively, and the experimental prototype is built. The experimental results show that the designed coupling magnetic element has positive effect on reducing the inductor current ripple and improving overall efficiency of the prototype.