Aiming at the problem that the traditional half-bridge Modular Multi-level Converters (MMC) cannot be controlled by the inverter itself to achieve DC fault blocking in the field of high-voltage power, a new Similarity Half Bridge Sub-Module (SHBSM) topology is proposed. It is need to block the entire IGBT pulse signal when the interpolar short-circuit fault occurs in the DC side. In order to reduce the technical requirements for IGBT simultaneously trigger, a mixed sub-module with SHBSM and Half Bridge Sub-Module (HBSM) is proposed without all IGBT blocking at the same time. The dual-ended MMC-HVDC system is built on the PSCAD/EMTDC simulation platform, the results show that the SHBSM-MMC and SHBSM-HBSM-MMC can effectively block the DC-side fault current and isolate the malfunction. Compared to the traditional HBSM-MMC, the SHBSM-MMC and SHBSM-HBSM-MMC don’t need to increase the investment of IGBT and it is possible to realize the effective blocking of the DC side fault current, therefore, the SHBSM-MMC and SHBSM-HBSM-MMC have good application prospects. This work is supported by National Natural Science Foundation of China (No. 51667013).