A hybrid modular multilevel converter （MMC） with full-bridge and half-bridge submodules can clear the DC fault through either converter-blocking or active-clearing approaches. However，there is still a lack of comprehensive analysis and comparison on the difference of fault-clearing characteristics，parameter design considerations and applicable occasions between the two approaches. Accurate dynamic models for the fault-clearing process of the converter-blocking and active-clearing approaches are established in this paper，respectively. Based on the established models，the effects of the distance of overhead lines and the proportion of full-bridge submodules on the fault-clearing time and the capacitor over-voltages are analyzed. The control strategy of the DC-link voltage and the submodule capacitor voltage for the active-clearing approach during fault-clearing process is proposed. Taking a 1 500 km long-distance DC transmission system based on hybrid MMCs as a case-study，the DC fault clearing process and performance of two fault-clearing approaches are compared through theoretical analysis simulations for various conditions. The main limiting factors of the two fault-clearing approaches are revealed and the principle for selecting DC fault-clearing strategies and the methodology for designing parameters of hybrid MMC are proposed.