This paper presents a novel Two-Level Series Resonant DC/DC Converter with Active Fault Isolation (TLSRSC-AFI), designed to address the limitations of traditional two-level DC/DC converters in high-power applications, such as high switching losses, significant voltage stress, and lack of fault-blocking capabilities. The proposed converter employs a modular structure with parallel front-end and series back-end configurations, integrating a two-level resonant main circuit and an Active Fault Isolation (AFI) interface. By incorporating resonant networks and soft-switching techniques, the converter significantly reduces switching losses and voltage stress, thereby enhancing conversion efficiency and power density. Additionally, the AFI enables rapid fault isolation during submodule failures or DC-side short circuits, preventing overcurrent and improving system robustness. This study provides a detailed analysis of the converter's operating principles and key parameter designs, and validates its advantages in efficiency, reliability, and dynamic response through simulations. The results demonstrate that the proposed topology achieves efficient energy conversion while offering fault-tolerant capabilities, presenting an economical and high-performance solution for Medium-Voltage Direct Current (MVDC) systems.