Abstract: The application in the practical engineering of modular multilevel converter based high voltage direct current（MMCHVDC） power grid based on half bridge submodules has been seriously restricted by the rapid increasement of DC short-circuit fault current. From the essence that the fault current limiter and grounding mode limit the current by increasing the fault circuit resistance or inductance, a comprehensive optimization method of fault current limiter and grounding mode based on transient energy flow（TEF） is proposed. This method takes the TEF suppression rate and suppression efficiency as the objective functions,and takes the fault current limiter, grounding mode and neutral reactance as the optimization variables, to construct the optimization model. Taking the four-terminal bipolar MMC-HVDC power grid as an example, the fault current limiter and grounding mode under single-pole-to-ground fault conditions on the DC side are optimized in PSCAD/EMTDC simulation system.The results show that the selected parameters can effectively reduce the DC fault current and bridge arm current, and provide a reference for the multi-parameter comprehensive optimal configuration of fault current limiter, grounding mode and neutral line reactance of DC grid considering the overvoltage constraints of normal poles.