Wave energy is a typical renewable energy, transferred into electric energy by permanent magnet synchronous generator (PMSG), and delivered in DC form. Thus, the power integration of multiple PMSGs is necessary. This paper proposes a coupled-inductor-based multiport DC integrated system to improve the intension and modularity of wave energy. The coupled inductor is employed to integrate submodules. The compact topology can further save the hardware cost. Then, the modality analysis is investigated in buck and boost modes. Moreover, the corresponding small-signal models are established. Finally, the operation waves and the frequency sweep results are discussed to verify the correct and effect of small-signal models.