The input voltage sharing (IVS) active control strategies of input-series output-parallel (ISOP) dual-active- bridge (DAB) converters have the problems of a complex control system and a large number of sensors. Passive approaches have concise control, and so have obvious advantages. Based on passive voltage balancing, a self-balancing topology with IVS for ISOP-DAB converter adopting coupling capacitors is proposed. Through coupling capacitors, the high-frequency-links of submodules are electrically coupled, thereby realizing the balance of input voltages of submodules. Also, a simplified equivalent circuit of the proposed ISOP-DAB converter with coupling capacitors is provided, and theoretical analysis and derivation are carried out to obtain the relationship between the input bus voltage deviation of the submodules and the coupling capacitor current to the converter parameters. The theoretical calculation results show that the proposed topology has better IVS capability in the presence of relatively large deviations among submodules. Finally, the feasibility and effectiveness of the proposed topology are verified by simulation and experiment.